diff --git a/SemanticData/Tests/USNodeSetValidationUnitTestProject/UANodeContextUnitTest.cs b/SemanticData/Tests/USNodeSetValidationUnitTestProject/UANodeContextUnitTest.cs
index 091a3b88..c45dc903 100644
--- a/SemanticData/Tests/USNodeSetValidationUnitTestProject/UANodeContextUnitTest.cs
+++ b/SemanticData/Tests/USNodeSetValidationUnitTestProject/UANodeContextUnitTest.cs
@@ -1,9 +1,9 @@
-//___________________________________________________________________________________
+//__________________________________________________________________________________________________
 //
-//  Copyright (C) 2021, Mariusz Postol LODZ POLAND.
+//  Copyright (C) 2022, Mariusz Postol LODZ POLAND.
 //
-//  To be in touch join the community at GITTER: https://gitter.im/mpostol/OPC-UA-OOI
-//___________________________________________________________________________________
+//  To be in touch join the community at GitHub: https://github.com/mpostol/OPC-UA-OOI/discussions
+//__________________________________________________________________________________________________
 
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using Moq;
@@ -195,8 +195,9 @@ public void CalculateNodeReferencesNullArguments()
       Mock<IValidator> _validatorMoc = new Mock<IValidator>();
       List<TraceMessage> _traceBuffer = new List<TraceMessage>();
       IUANodeBase _first = new UANodeContext(NodeId.Parse("ns=1;i=11"), _addressSpaceMock.Object, x => _traceBuffer.Add(x));
-      Assert.ThrowsException<ArgumentNullException>(() => _first.CalculateNodeReferences(null, _validatorMoc.Object));
-      Assert.ThrowsException<ArgumentNullException>(() => _first.CalculateNodeReferences(_mockNodeFactory.Object, null));
+      Assert.ThrowsException<ArgumentNullException>(() => _first.CalculateNodeReferences(null, _validatorMoc.Object, y => { }));
+      Assert.ThrowsException<ArgumentNullException>(() => _first.CalculateNodeReferences(_mockNodeFactory.Object, null, y => { }));
+      Assert.ThrowsException<ArgumentNullException>(() => _first.CalculateNodeReferences(_mockNodeFactory.Object, _validatorMoc.Object, null));
     }
 
     [TestMethod]
@@ -233,14 +234,17 @@ public void CalculateNodeReferencesNullUANodeTest()
       Mock<INodeFactory> _mockNodeFactory = new Mock<INodeFactory>();
       _mockNodeFactory.Setup(x => x.NewReference()).Returns(referenceFactoryMock.Object);
       Mock<IValidator> _validatorMoc = new Mock<IValidator>();
-      _validatorMoc.Setup(x => x.ValidateExportNode(It.IsAny<IUANodeBase>(), _mockNodeFactory.Object, It.IsAny<UAReferenceContext>()));
+      _validatorMoc.Setup(x => x.ValidateExportNode(It.IsAny<IUANodeBase>(), _mockNodeFactory.Object, It.IsAny<Action<IUANodeContext>>(), It.IsAny<UAReferenceContext>()));
 
       //testing
-      ((IUANodeBase)node2Test).CalculateNodeReferences(_mockNodeFactory.Object, _validatorMoc.Object);
+      int counter = 0;
+      ((IUANodeBase)node2Test).CalculateNodeReferences(_mockNodeFactory.Object, _validatorMoc.Object, y => counter++);
+      
       //validation
+      Assert.AreEqual<int>(1, counter);
       addressSpaceMock.Verify(x => x.GetMyReferences(It.IsAny<IUANodeBase>()), Times.Once);
       addressSpaceMock.Verify(x => x.ExportBrowseName(It.IsAny<NodeId>(), It.IsAny<NodeId>()), Times.Once);
-      _validatorMoc.Verify(x => x.ValidateExportNode(It.IsAny<IUANodeBase>(), _mockNodeFactory.Object, It.IsAny<UAReferenceContext>()), Times.Never);
+      _validatorMoc.Verify(x => x.ValidateExportNode(It.Is<IUANodeBase>(z => z == targetMock.Object), _mockNodeFactory.Object, It.IsAny<Action<IUANodeContext>>(), It.Is<UAReferenceContext>(y => y == listOfReferences[0])), Times.Never);
       Assert.AreEqual<int>(0, _traceBuffer.Count, _traceBuffer.Count == 0 ? "" : _traceBuffer[0].Message);
     }
 
diff --git a/SemanticData/Tests/USNodeSetValidationUnitTestProject/ValidatorUnitTest.cs b/SemanticData/Tests/USNodeSetValidationUnitTestProject/ValidatorUnitTest.cs
index 2a9d4179..84b357a6 100644
--- a/SemanticData/Tests/USNodeSetValidationUnitTestProject/ValidatorUnitTest.cs
+++ b/SemanticData/Tests/USNodeSetValidationUnitTestProject/ValidatorUnitTest.cs
@@ -1,6 +1,6 @@
 //__________________________________________________________________________________________________
 //
-//  Copyright (C) 2021, Mariusz Postol LODZ POLAND.
+//  Copyright (C) 2022, Mariusz Postol LODZ POLAND.
 //
 //  To be in touch join the community at GitHub: https://github.com/mpostol/OPC-UA-OOI/discussions
 //__________________________________________________________________________________________________
@@ -56,7 +56,7 @@ public void UAMethodTest()
         DisplayName = new LocalizedText[] { new LocalizedText() { Value = "Start" } },
         References = new Reference[] { }
       };
-      List<TraceMessage> traceBuffer = new List<TraceMessage>(); 
+      List<TraceMessage> traceBuffer = new List<TraceMessage>();
       UANodeContext nodeContext = new UANodeContext(DataSerialization.NodeId.Parse(method.NodeId), addressSpaceBuildContextMock.Object, x => traceBuffer.Add(x));
       nodeContext.Update(method, x => { });
       Mock<INodeContainer> nodeContainerMock = new Mock<INodeContainer>();
@@ -64,7 +64,7 @@ public void UAMethodTest()
       nodeContainerMock.Setup(x => x.AddNodeFactory<IMethodInstanceFactory>()).Returns(methodInstanceFactory.Object);
       //TODO UANodeSetValidation.Extensions.GetObject - object reference not set #624
       Assert.Inconclusive("UANodeSetValidation.Extensions.GetObject - object reference not set #624");
-      _i2t.ValidateExportNode(nodeContext, nodeContainerMock.Object);
+      _i2t.ValidateExportNode(nodeContext, nodeContainerMock.Object, z => { });
       Assert.AreEqual<int>(0, traceBuffer.Count);
     }
   }
diff --git a/SemanticData/UANodeSetValidation/AddressSpaceContext.cs b/SemanticData/UANodeSetValidation/AddressSpaceContext.cs
index 0efcd3ce..34d727ef 100644
--- a/SemanticData/UANodeSetValidation/AddressSpaceContext.cs
+++ b/SemanticData/UANodeSetValidation/AddressSpaceContext.cs
@@ -312,16 +312,17 @@ private IUANodeContext TryGetUANodeContext(NodeId nodeId)
       return _ret;
     }
 
+    //TODO NetworkIdentifier is missing in generated Model Design for DI model #629
     private void ValidateAndExportModel(int nameSpaceIndex)
     {
       IValidator validator = new Validator(this, m_TraceEvent);
-      IEnumerable<IUANodeContext> stubs = from _key in m_NodesDictionary.Values where _key.NodeIdContext.NamespaceIndex == nameSpaceIndex select _key;
-      IEnumerable<IUANodeContext> undefindNodes = from node in stubs
-                                                  where Object.ReferenceEquals(node.UANode, null)
-                                                  select node;
-      foreach (IUANodeContext item in undefindNodes)
+      IEnumerable<IUANodeBase> stubs = from _key in m_NodesDictionary.Values where _key.NodeIdContext.NamespaceIndex == nameSpaceIndex select _key;
+      IEnumerable<IUANodeBase> undefindNodes = from node in stubs
+                                               where Object.ReferenceEquals(node.UANode, null)
+                                               select node;
+      foreach (IUANodeBase item in undefindNodes)
         m_TraceEvent.WriteTraceMessage(TraceMessage.BuildErrorTraceMessage(BuildError.NodeCannotBeNull, $"the node {item.ToString()} is not defined in the UANodeSet model"));
-      List<IUANodeContext> nodes = (from _node in stubs where _node.UANode != null && (_node.UANode is UAType) select _node).ToList();
+      List<IUANodeBase> nodes = (from _node in stubs where _node.UANode != null && (_node.UANode is UAType) select _node).ToList();
       m_TraceEvent.TraceData(TraceEventType.Verbose, 938023414, $"Selected {nodes.Count} types to be validated.");
       IUANodeBase _objects = TryGetUANodeContext(UAInformationModel.ObjectIds.ObjectsFolder);
       if (_objects is null)
@@ -338,18 +339,24 @@ where Object.ReferenceEquals(node.UANode, null)
         string _version = modelTableEntry.Version;
         InformationModelFactory.CreateNamespace(modelTableEntry.ModelUri.ToString(), _publicationDate, _version);
       }
-      foreach (IUANodeBase item in nodes)
+      //NetworkIdentifier is missing in generated Model Design for DI model #629
+      do
       {
-        try
-        {
-          validator.ValidateExportNode(item, InformationModelFactory);
-        }
-        catch (Exception ex)
+        NodesCollection embededNodes = new NodesCollection();
+        foreach (IUANodeBase item in nodes)
         {
-          string msg = string.Format("Error caught while processing the node {0}. The message: {1} at {2}.", item.UANode.NodeId, ex.Message, ex.StackTrace);
-          m_TraceEvent.WriteTraceMessage(TraceMessage.BuildErrorTraceMessage(BuildError.NonCategorized, msg));
+          try
+          {
+            validator.ValidateExportNode(item, InformationModelFactory, y => { if (y.NodeIdContext.NamespaceIndex == nameSpaceIndex) embededNodes.AddOrReplace(y, false); });
+          }
+          catch (Exception ex)
+          {
+            string msg = string.Format("Error caught while processing the node {0}. The message: {1} at {2}.", item.UANode.NodeId, ex.Message, ex.StackTrace);
+            m_TraceEvent.WriteTraceMessage(TraceMessage.BuildErrorTraceMessage(BuildError.NonCategorized, msg));
+          }
         }
-      }
+        nodes = embededNodes.ToList();
+      } while (nodes.Count > 0);
       string message = null;
       if (m_TraceEvent.Errors == 0)
       {
diff --git a/SemanticData/UANodeSetValidation/IUANodeBase.cs b/SemanticData/UANodeSetValidation/IUANodeBase.cs
index c1e7aaba..753e38f8 100644
--- a/SemanticData/UANodeSetValidation/IUANodeBase.cs
+++ b/SemanticData/UANodeSetValidation/IUANodeBase.cs
@@ -1,12 +1,11 @@
-//___________________________________________________________________________________
+//__________________________________________________________________________________________________
 //
-//  Copyright (C) 2021, Mariusz Postol LODZ POLAND.
+//  Copyright (C) 2022, Mariusz Postol LODZ POLAND.
 //
-//  To be in touch join the community at GITTER: https://gitter.im/mpostol/OPC-UA-OOI
-//___________________________________________________________________________________
+//  To be in touch join the community at GitHub: https://github.com/mpostol/OPC-UA-OOI/discussions
+//__________________________________________________________________________________________________
 
 using System;
-using System.Collections.Generic;
 using System.Xml;
 using UAOOI.SemanticData.InformationModelFactory;
 using UAOOI.SemanticData.UANodeSetValidation.DataSerialization;
@@ -14,63 +13,72 @@
 
 namespace UAOOI.SemanticData.UANodeSetValidation
 {
-
   /// <summary>
   /// Interface IUANodeBase - if implemented captures all basic information represented by the UA Node
   /// </summary>
-  internal interface IUANodeBase: IEquatable<IUANodeBase>
+  internal interface IUANodeBase : IEquatable<IUANodeBase>
   {
-
     /// <summary>
     /// Calculates the node references.
     /// </summary>
     /// <param name="nodeFactory">The node factory.</param>
     /// <param name="validator">The validator.</param>
-    void CalculateNodeReferences(INodeFactory nodeFactory, IValidator validator);
+    /// <param name="validateExportNode2Model">It creates the node at the top level of the model. Called if the node has reference to another node that cannot be defined as a child.</param>
+    void CalculateNodeReferences(INodeFactory nodeFactory, IValidator validator, Action<IUANodeContext> validateExportNode2Model);
+
     /// <summary>
     /// Gets the node identifier.
     /// </summary>
     /// <value>The imported node identifier.</value>
     NodeId NodeIdContext { get; }
+
     /// <summary>
     /// Gets the wrapped node described by the <see cref="UANode"/> type.
     /// </summary>
     UANode UANode { get; }
+
     /// <summary>
     /// Exports the browse name of the wrapped node by this instance.
     /// </summary>
     /// <returns>An instance of <see cref="XmlQualifiedName" /> representing the browse name of the node.</returns>
     XmlQualifiedName ExportNodeBrowseName();
+
     /// <summary>
     /// Gets a value indicating whether this instance is a property.
     /// </summary>
     /// <value><c>true</c> if this instance is property; otherwise, <c>false</c>.</value>
     bool IsProperty { get; }
+
     /// <summary>
     /// Gets a value indicating whether this instance is property variable type.
     /// </summary>
     /// <value><c>true</c> if this instance is property variable type; otherwise, <c>false</c>.</value>
     bool IsPropertyVariableType { get; }
+
     /// <summary>
     /// Exports the browse name of this node recognized as <see cref="ReferenceKindEnum.HasSubtype"/> or <see cref="ReferenceKindEnum.HasTypeDefinition"/> target.
     /// </summary>
     /// <param name="traceEvent">The trace event.</param>
     /// <returns>An instance of <see cref="XmlQualifiedName"/> representing subtype or type of an instance.</returns>
     XmlQualifiedName ExportBrowseNameBaseType(Action<NodeId> traceEvent);
+
     /// <summary>
     /// Gets the derived instances.
     /// </summary>
-    Dictionary<string, IUANodeBase> GetDerivedInstances();
+    NodesCollection GetDerivedInstances();
+
     /// <summary>
     ///  Exports the BrowseName of the BaseType.
     /// </summary>
     /// <returns>An instance of <see cref="XmlQualifiedName" /> representing the base type..</returns>
     XmlQualifiedName ExportBaseTypeBrowseName();
+
     /// <summary>
     /// Gets the modeling rule associated with this node.
     /// </summary>
     /// <value>The <see cref="ModelingRules"/> associated with the node. Null if valid modeling rule cannot be recognized.</value>
     ModelingRules? ModelingRule { get; }
+
     /// <summary>
     /// Removes the inherited values.
     /// </summary>
@@ -79,6 +87,5 @@ internal interface IUANodeBase: IEquatable<IUANodeBase>
     /// If a member is overridden all inherited values of the node attributes must be removed.
     /// </remarks>
     void RemoveInheritedValues(IUANodeBase instanceDeclaration);
-
   }
-}
+}
\ No newline at end of file
diff --git a/SemanticData/UANodeSetValidation/IValidator.cs b/SemanticData/UANodeSetValidation/IValidator.cs
index e1202943..1d78aa1f 100644
--- a/SemanticData/UANodeSetValidation/IValidator.cs
+++ b/SemanticData/UANodeSetValidation/IValidator.cs
@@ -1,10 +1,11 @@
-//___________________________________________________________________________________
+//__________________________________________________________________________________________________
 //
-//  Copyright (C) 2021, Mariusz Postol LODZ POLAND.
+//  Copyright (C) 2022, Mariusz Postol LODZ POLAND.
 //
-//  To be in touch join the community at GITTER: https://gitter.im/mpostol/OPC-UA-OOI
-//___________________________________________________________________________________
+//  To be in touch join the community at GitHub: https://github.com/mpostol/OPC-UA-OOI/discussions
+//__________________________________________________________________________________________________
 
+using System;
 using UAOOI.SemanticData.InformationModelFactory;
 
 namespace UAOOI.SemanticData.UANodeSetValidation
@@ -20,13 +21,15 @@ internal interface IValidator
     /// <param name="nodeContext">The node context to be validated and exported.</param>
     /// <param name="exportFactory">A model export factory.</param>
     /// <param name="parentReference">The reference to parent node.</param>
-    void ValidateExportNode(IUANodeBase nodeContext, INodeContainer exportFactory, UAReferenceContext parentReference);
+    /// <param name="validateExportNode2Model">It creates the node at the top level of the model. Called if the node has reference to another node that cannot be defined as a child.</param>
+    void ValidateExportNode(IUANodeBase nodeContext, INodeContainer exportFactory, Action<IUANodeContext> validateExportNode2Model, UAReferenceContext parentReference);
 
     /// <summary>
     /// Validates <paramref name="nodeContext" /> and exports it using an object of <see cref="IModelFactory" />  type.
     /// </summary>
     /// <param name="nodeContext">The node context to be validated and exported.</param>
     /// <param name="exportFactory">A model export factory.</param>
-    void ValidateExportNode(IUANodeBase nodeContext, INodeContainer exportFactory);
+    /// <param name="validateExportNode2Model">It creates the node at the top level of the model. Called if the node has reference to another node that cannot be defined as a child.</param>
+    void ValidateExportNode(IUANodeBase nodeContext, INodeContainer exportFactory, Action<IUANodeContext> validateExportNode2Model);
   }
 }
\ No newline at end of file
diff --git a/SemanticData/UANodeSetValidation/ReferenceKindEnum.cs b/SemanticData/UANodeSetValidation/ReferenceKindEnum.cs
index 2eaa51c0..b395c8cc 100644
--- a/SemanticData/UANodeSetValidation/ReferenceKindEnum.cs
+++ b/SemanticData/UANodeSetValidation/ReferenceKindEnum.cs
@@ -1,11 +1,10 @@
 //__________________________________________________________________________________________________
 //
-//  Copyright (C) 2021, Mariusz Postol LODZ POLAND.
+//  Copyright (C) 2022, Mariusz Postol LODZ POLAND.
 //
 //  To be in touch join the community at GitHub: https://github.com/mpostol/OPC-UA-OOI/discussions
 //__________________________________________________________________________________________________
 
-
 namespace UAOOI.SemanticData.UANodeSetValidation
 {
   /// <summary>
@@ -33,11 +32,6 @@ internal enum ReferenceKindEnum
     /// </summary>
     HasTypeDefinition,
 
-    /// <summary>
-    /// The HierarchicalReferences
-    /// </summary>
-    HierarchicalReferences,
-
     /// <summary>
     /// The HasSubtype
     /// </summary>
diff --git a/SemanticData/UANodeSetValidation/UANodeContext.cs b/SemanticData/UANodeSetValidation/UANodeContext.cs
index ee3def26..3afc8133 100644
--- a/SemanticData/UANodeSetValidation/UANodeContext.cs
+++ b/SemanticData/UANodeSetValidation/UANodeContext.cs
@@ -47,6 +47,7 @@ internal UANodeContext(NodeId nodeId, IAddressSpaceBuildContext addressSpaceCont
     /// Builds the symbolic identifier.
     /// </summary>
     /// <param name="path">The browse path.</param>
+    //NetworkIdentifier is missing in generated Model Design for DI model #629
     public void BuildSymbolicId(List<string> path)
     {
       if (this.UANode == null)
@@ -95,8 +96,6 @@ public void Update(UANode node, Action<UAReferenceContext> addReference)
           case ReferenceKindEnum.Custom:
           case ReferenceKindEnum.HasComponent:
           case ReferenceKindEnum.HasProperty:
-          //NetworkIdentifier is missing in generated Model Design for DI model #629
-          case ReferenceKindEnum.HierarchicalReferences:
             break;
 
           case ReferenceKindEnum.HasModellingRule:
@@ -134,18 +133,20 @@ public XmlQualifiedName ExportNodeBrowseName()
     }
 
     /// <summary>
-    /// Processes the node references to calculate all relevant properties. Must be called after finishing import of all the parent models.
+    /// Calculates the node references.
     /// </summary>
-    /// <param name="nodeFactory">The node container.</param>
+    /// <param name="nodeFactory">The node factory.</param>
     /// <param name="validator">The validator.</param>
-    /// <exception cref="ArgumentNullException"><paramref name="nodeFactory"/> must not be null.</exception>
+    /// <param name="validateExportNode2Model">It creates the node at the top level of the model. Called if the node has reference to another node that cannot be defined as a child.</param>
     //TODO Import simple NodeSet2 file is incomplete #510
-    void IUANodeBase.CalculateNodeReferences(INodeFactory nodeFactory, IValidator validator)
+    void IUANodeBase.CalculateNodeReferences(INodeFactory nodeFactory, IValidator validator, Action<IUANodeContext> validateExportNode2Model)
     {
       if (nodeFactory == null)
         throw new ArgumentNullException(nameof(nodeFactory), $"{nodeFactory} must not be null in {nameof(IUANodeBase.CalculateNodeReferences)}");
       if (validator is null)
         throw new ArgumentNullException(nameof(validator), $"{nameof(validator)} must not be null in {nameof(IUANodeBase.CalculateNodeReferences)}");
+      if (validateExportNode2Model == null)
+        throw new ArgumentNullException(nameof(validateExportNode2Model), $"The parameter must not be null in {nameof(IUANodeBase.CalculateNodeReferences)}");
       List<UAReferenceContext> _children = new List<UAReferenceContext>();
       foreach (UAReferenceContext _rfx in m_AddressSpaceContext.GetMyReferences(this))
       {
@@ -157,7 +158,6 @@ void IUANodeBase.CalculateNodeReferences(INodeFactory nodeFactory, IValidator va
         switch (_rfx.ReferenceKind)
         {
           case ReferenceKindEnum.Custom:
-            //TODO NetworkIdentifier is missing in generated Model Design for DI model #629
             XmlQualifiedName _ReferenceType = _rfx.GetReferenceTypeName();
             if (_ReferenceType == XmlQualifiedName.Empty)
             {
@@ -172,8 +172,8 @@ void IUANodeBase.CalculateNodeReferences(INodeFactory nodeFactory, IValidator va
             IReferenceFactory _or = nodeFactory.NewReference();
             _or.IsInverse = !_rfx.IsForward;
             _or.ReferenceType = _ReferenceType;
+            //TODO NetworkIdentifier is missing in generated Model Design for DI model #629
             _or.TargetId = _rfx.BrowsePath();
-            //switch (_rfx.TargetNode.UANode.NodeClassEnum)
             switch (_rfx.TargetNode.UANode.NodeClassEnum)
             {
               case NodeClassEnum.UADataType:
@@ -181,20 +181,32 @@ void IUANodeBase.CalculateNodeReferences(INodeFactory nodeFactory, IValidator va
               case NodeClassEnum.UAReferenceType:
               case NodeClassEnum.UAVariableType:
                 break;
+
               case NodeClassEnum.UAMethod:
+                _TraceEvent(TraceMessage.DiagnosticTraceMessage($"Removed the graph of nodes at {_rfx.TargetNode} from the model"));
                 //validator..ValidateExportNode(_rc.TargetNode, nodeFactory, _rc);
                 break;
+
               case NodeClassEnum.UAObject:
+                validateExportNode2Model(_rfx.TargetNode);
+                //validator.ValidateExportNode(_rfx.TargetNode, nodeFactory, _rfx);
                 break;
+
+              //TODO NetworkIdentifier is missing in generated Model Design for DI model #629
               case NodeClassEnum.UAVariable:
+                _TraceEvent(TraceMessage.DiagnosticTraceMessage($"Removed the graph of nodes at {_rfx.TargetNode} from the model"));
                 break;
+
               case NodeClassEnum.UAView:
+                _TraceEvent(TraceMessage.DiagnosticTraceMessage($"Removed the graph of nodes at {_rfx.TargetNode} from the model"));
                 break;
-              case NodeClassEnum.Unknown:
 
+              case NodeClassEnum.Unknown:
+                _TraceEvent(TraceMessage.DiagnosticTraceMessage($"Removed the graph of nodes at {_rfx.TargetNode} from the model"));
                 break;
+
               default:
-                break;
+                throw new ArgumentOutOfRangeException(nameof(_rfx.TargetNode.UANode.NodeClassEnum));
             }
             break;
 
@@ -215,14 +227,6 @@ void IUANodeBase.CalculateNodeReferences(INodeFactory nodeFactory, IValidator va
           case ReferenceKindEnum.HasTypeDefinition: //TODO Recognize problems with P3.7.13 HasTypeDefinition ReferenceType #39
             IsProperty = _rfx.TargetNode.IsPropertyVariableType;
             break;
-
-          case ReferenceKindEnum.HierarchicalReferences:
-            //TODO NetworkIdentifier is missing in generated Model Design for DI model #629
-            XmlQualifiedName referenceType = _rfx.GetReferenceTypeName();
-            string message =
-              $"Id = D290E7B4-F77C-4EF0-883B-844F66471DB6; Reference {nameof(ReferenceKindEnum.HierarchicalReferences)} is not supported. Removed the graph at {referenceType.ToString()} of nodes from the model";
-            _TraceEvent(TraceMessage.BuildErrorTraceMessage(BuildError.DiagnosticInformation, message));
-            break;
         }
       }
       Dictionary<string, IUANodeBase> _derivedChildren = m_BaseTypeNode == null ? new Dictionary<string, IUANodeBase>() : m_BaseTypeNode.GetDerivedInstances();
@@ -239,7 +243,7 @@ void IUANodeBase.CalculateNodeReferences(INodeFactory nodeFactory, IValidator va
             continue;
           }
           _rc.TargetNode.RemoveInheritedValues(_instanceDeclaration);
-          validator.ValidateExportNode(_rc.TargetNode, nodeFactory, _rc);
+          validator.ValidateExportNode(_rc.TargetNode, nodeFactory, validateExportNode2Model, _rc);
         }
         catch (Exception) { throw; }
       }
@@ -307,7 +311,7 @@ public XmlQualifiedName ExportBrowseNameBaseType(Action<NodeId> traceEvent)
     /// <returns>Dictionary&lt;System.String, IUANodeBase&gt;.</returns>
     /// <exception cref="ArgumentOutOfRangeException">Circular loop in inheritance chain</exception>
     //TODO NetworkIdentifier is missing in generated Model Design for DI model #629
-    public Dictionary<string, IUANodeBase> GetDerivedInstances()
+    public NodesCollection GetDerivedInstances()
     {
       if (m_InGetDerivedInstances)
         //Improve GetDerivedInstances to log a message instead of throwing exception #651
@@ -316,15 +320,9 @@ public Dictionary<string, IUANodeBase> GetDerivedInstances()
       {
         m_InGetDerivedInstances = true;
         IEnumerable<IUANodeBase> _myChildren = m_AddressSpaceContext.GetChildren(this);
-        Dictionary<string, IUANodeBase> _instanceDeclarations = m_BaseTypeNode == null ? new Dictionary<string, IUANodeBase>() : m_BaseTypeNode.GetDerivedInstances();
-        foreach (UANodeContext item in _myChildren)
-        {
-          string _key = item.UANode.BrowseNameQualifiedName.Name;
-          if (_instanceDeclarations.ContainsKey(_key))
-            _instanceDeclarations[_key] = item; //replace by current item that overrides the base one
-          else
-            _instanceDeclarations.Add(_key, item); //add derived item
-        }
+        NodesCollection _instanceDeclarations = m_BaseTypeNode == null ? new NodesCollection() : m_BaseTypeNode.GetDerivedInstances();
+        foreach (IUANodeBase item in _myChildren)
+          _instanceDeclarations.AddOrReplace(item, true);
         return _instanceDeclarations;
       }
       finally
diff --git a/SemanticData/UANodeSetValidation/UAReferenceContext.cs b/SemanticData/UANodeSetValidation/UAReferenceContext.cs
index 04e37f16..18d49b0d 100644
--- a/SemanticData/UANodeSetValidation/UAReferenceContext.cs
+++ b/SemanticData/UANodeSetValidation/UAReferenceContext.cs
@@ -48,7 +48,6 @@ internal UAReferenceContext(Reference reference, IAddressSpaceBuildContext addre
     /// Gets the kind of the reference.
     /// </summary>
     /// <value>The kind of the reference.</value>
-    //TODO NetworkIdentifier is missing in generated Model Design for DI model #629
     internal ReferenceKindEnum ReferenceKind
     {
       get
@@ -116,7 +115,7 @@ internal XmlQualifiedName BrowsePath()
     }
 
     /// <summary>
-    /// Ir recursively builds the symbolic identifier.
+    /// It recursively builds the symbolic identifier.
     /// </summary>
     /// <param name="path">The browse path.</param>
     internal void BuildSymbolicId(List<string> path)
@@ -189,9 +188,6 @@ private ReferenceKindEnum CalculateReferenceKind()
         _ret = ReferenceKindEnum.HasComponent;
       else if (inheritanceChain.Where<IUANodeContext>(x => x.NodeIdContext == ReferenceTypeIds.HasSubtype).Any<IUANodeContext>())
         _ret = ReferenceKindEnum.HasSubtype;
-      //TODO NetworkIdentifier is missing in generated Model Design for DI model #629
-      else if (inheritanceChain.Where<IUANodeContext>(x => x.NodeIdContext == ReferenceTypeIds.HierarchicalReferences).Any<IUANodeContext>())
-        _ret = ReferenceKindEnum.HierarchicalReferences;
       else if (inheritanceChain.Where<IUANodeContext>(x => x.NodeIdContext == ReferenceTypeIds.HasTypeDefinition).Any<IUANodeContext>())
         _ret = ReferenceKindEnum.HasTypeDefinition;
       else if (inheritanceChain.Where<IUANodeContext>(x => x.NodeIdContext == ReferenceTypeIds.HasModellingRule).Any<IUANodeContext>())
diff --git a/SemanticData/UANodeSetValidation/Validator.cs b/SemanticData/UANodeSetValidation/Validator.cs
index d545a000..bc00c763 100644
--- a/SemanticData/UANodeSetValidation/Validator.cs
+++ b/SemanticData/UANodeSetValidation/Validator.cs
@@ -1,6 +1,6 @@
 //__________________________________________________________________________________________________
 //
-//  Copyright (C) 2021, Mariusz Postol LODZ POLAND.
+//  Copyright (C) 2022, Mariusz Postol LODZ POLAND.
 //
 //  To be in touch join the community at GitHub: https://github.com/mpostol/OPC-UA-OOI/discussions
 //__________________________________________________________________________________________________
@@ -31,16 +31,17 @@ internal Validator(IAddressSpaceBuildContext addressSpace, IBuildErrorsHandling
       m_buildErrorsHandling = traceBuildErrorsHandling;
     }
 
-    #region internal API
+    #region IValidator
 
     /// <summary>
     /// Validates <paramref name="nodeContext" /> and exports it using an object of <see cref="IModelFactory" />  type.
     /// </summary>
     /// <param name="nodeContext">The node context to be validated and exported.</param>
     /// <param name="exportFactory">A model export factory.</param>
-    public void ValidateExportNode(IUANodeBase nodeContext, INodeContainer exportFactory)
+    /// <param name="validateExportNode2Model">It creates the node at the top level of the model. Called if the node has reference to another node that cannot be defined as a child.</param>
+    public void ValidateExportNode(IUANodeBase nodeContext, INodeContainer exportFactory, Action<IUANodeContext> validateExportNode2Model)
     {
-      ValidateExportNode(nodeContext, exportFactory, null);
+      ValidateExportNode(nodeContext, exportFactory, validateExportNode2Model, null);
     }
 
     /// <summary>
@@ -49,7 +50,8 @@ public void ValidateExportNode(IUANodeBase nodeContext, INodeContainer exportFac
     /// <param name="nodeContext">The node context to be validated and exported.</param>
     /// <param name="exportFactory">A model export factory.</param>
     /// <param name="parentReference">The reference to parent node.</param>
-    public void ValidateExportNode(IUANodeBase nodeContext, INodeContainer exportFactory, UAReferenceContext parentReference)
+    /// <param name="validateExportNode2Model">It creates the node at the top level of the model. Called if the node has reference to another node that cannot be defined as a child.</param>
+    public void ValidateExportNode(IUANodeBase nodeContext, INodeContainer exportFactory, Action<IUANodeContext> validateExportNode2Model, UAReferenceContext parentReference)
     {
       Debug.Assert(nodeContext != null, "Validator.ValidateExportNode the argument nodeContext is null.");
       //TODO Handle HasComponent ReferenceType errors. #42
@@ -70,38 +72,38 @@ public void ValidateExportNode(IUANodeBase nodeContext, INodeContainer exportFac
         switch (nodeContext.UANode.NodeClassEnum)
         {
           case NodeClassEnum.UADataType:
-            CreateNode<IDataTypeFactory, UADataType>(exportFactory.AddNodeFactory<IDataTypeFactory>, nodeContext, (x, y) => Update(x, y), UpdateType);
+            CreateNode<IDataTypeFactory, UADataType>(exportFactory.AddNodeFactory<IDataTypeFactory>, nodeContext, (x, y) => Update(x, y), UpdateType, validateExportNode2Model);
             break;
 
           case NodeClassEnum.UAMethod:
-            CreateNode<IMethodInstanceFactory, UAMethod>(exportFactory.AddNodeFactory<IMethodInstanceFactory>, nodeContext, (x, y) => Update(x, y, parentReference), UpdateInstance);
+            CreateNode<IMethodInstanceFactory, UAMethod>(exportFactory.AddNodeFactory<IMethodInstanceFactory>, nodeContext, (x, y) => Update(x, y, parentReference), UpdateInstance, validateExportNode2Model);
             break;
 
           case NodeClassEnum.UAObject:
-            CreateNode<IObjectInstanceFactory, UAObject>(exportFactory.AddNodeFactory<IObjectInstanceFactory>, nodeContext, (x, y) => Update(x, y), UpdateInstance);
+            CreateNode<IObjectInstanceFactory, UAObject>(exportFactory.AddNodeFactory<IObjectInstanceFactory>, nodeContext, (x, y) => Update(x, y), UpdateInstance, validateExportNode2Model);
             break;
 
           case NodeClassEnum.UAObjectType:
-            CreateNode<IObjectTypeFactory, UAObjectType>(exportFactory.AddNodeFactory<IObjectTypeFactory>, nodeContext, Update, UpdateType);
+            CreateNode<IObjectTypeFactory, UAObjectType>(exportFactory.AddNodeFactory<IObjectTypeFactory>, nodeContext, Update, UpdateType, validateExportNode2Model);
             break;
 
           case NodeClassEnum.UAReferenceType:
-            CreateNode<IReferenceTypeFactory, UAReferenceType>(exportFactory.AddNodeFactory<IReferenceTypeFactory>, nodeContext, (x, y) => Update(x, y), UpdateType);
+            CreateNode<IReferenceTypeFactory, UAReferenceType>(exportFactory.AddNodeFactory<IReferenceTypeFactory>, nodeContext, (x, y) => Update(x, y), UpdateType, validateExportNode2Model);
             break;
 
           case NodeClassEnum.UAVariable:
             if (parentReference.ReferenceKind == ReferenceKindEnum.HasProperty)
-              CreateNode<IPropertyInstanceFactory, UAVariable>(exportFactory.AddNodeFactory<IPropertyInstanceFactory>, nodeContext, (x, y) => Update(x, y, nodeContext, parentReference), UpdateInstance);
+              CreateNode<IPropertyInstanceFactory, UAVariable>(exportFactory.AddNodeFactory<IPropertyInstanceFactory>, nodeContext, (x, y) => Update(x, y, nodeContext, parentReference), UpdateInstance, validateExportNode2Model);
             else
-              CreateNode<IVariableInstanceFactory, UAVariable>(exportFactory.AddNodeFactory<IVariableInstanceFactory>, nodeContext, (x, y) => Update(x, y, nodeContext, parentReference), UpdateInstance);
+              CreateNode<IVariableInstanceFactory, UAVariable>(exportFactory.AddNodeFactory<IVariableInstanceFactory>, nodeContext, (x, y) => Update(x, y, nodeContext, parentReference), UpdateInstance, validateExportNode2Model);
             break;
 
           case NodeClassEnum.UAVariableType:
-            CreateNode<IVariableTypeFactory, UAVariableType>(exportFactory.AddNodeFactory<IVariableTypeFactory>, nodeContext, (x, y) => Update(x, y), UpdateType);
+            CreateNode<IVariableTypeFactory, UAVariableType>(exportFactory.AddNodeFactory<IVariableTypeFactory>, nodeContext, (x, y) => Update(x, y), UpdateType, validateExportNode2Model);
             break;
 
           case NodeClassEnum.UAView:
-            CreateNode<IViewInstanceFactory, UAView>(exportFactory.AddNodeFactory<IViewInstanceFactory>, nodeContext, (x, y) => Update(x, y), UpdateInstance);
+            CreateNode<IViewInstanceFactory, UAView>(exportFactory.AddNodeFactory<IViewInstanceFactory>, nodeContext, (x, y) => Update(x, y), UpdateInstance, validateExportNode2Model);
             break;
 
           case NodeClassEnum.Unknown:
@@ -110,7 +112,7 @@ public void ValidateExportNode(IUANodeBase nodeContext, INodeContainer exportFac
       }
     }
 
-    #endregion internal API
+    #endregion IValidator
 
     #region private
 
@@ -245,13 +247,14 @@ private void CreateNode<FactoryType, NodeSetType>
         Func<FactoryType> createNode,
         IUANodeBase nodeContext,
         Action<FactoryType, NodeSetType> updateNode,
-        Action<FactoryType, NodeSetType, IUANodeBase> updateBase
+        Action<FactoryType, NodeSetType, IUANodeBase> updateBase,
+        Action<IUANodeContext> validateExportNode2Model
       )
       where FactoryType : INodeFactory
       where NodeSetType : UANode
     {
       FactoryType _nodeFactory = createNode();
-      nodeContext.CalculateNodeReferences(_nodeFactory, this);
+      nodeContext.CalculateNodeReferences(_nodeFactory, this, validateExportNode2Model);
       NodeSetType _nodeSet = (NodeSetType)nodeContext.UANode;
       XmlQualifiedName _browseName = nodeContext.ExportNodeBrowseName();
       string _symbolicName;