diff --git a/src/Moryx.ControlSystem/Processes/ProcessHolderExtensions.cs b/src/Moryx.ControlSystem/Processes/ProcessHolderExtensions.cs
index abd8d03..bc65de3 100644
--- a/src/Moryx.ControlSystem/Processes/ProcessHolderExtensions.cs
+++ b/src/Moryx.ControlSystem/Processes/ProcessHolderExtensions.cs
@@ -18,6 +18,12 @@ public static class ProcessHolderExtensions
         public static TPosition GetPositionByIdentifier<TPosition>(this IProcessHolderGroup<TPosition> group, string identifier)
             where TPosition : IProcessHolderPosition => GetPosition(group.Positions, t => t.Identifier == identifier);
 
+        /// <summary>
+        /// Get the position by its <see cref="IProcessHolderPosition.Identifier"/>
+        /// </summary>
+        public static IProcessHolderPosition GetPositionByIdentifier(this IProcessHolderGroup group, string identifier)
+            => GetPosition(group.Positions, t => t.Identifier == identifier);
+
         /// <summary>
         /// Get the position by its <see cref="IProcessHolderPosition.Identifier"/>
         /// </summary>
@@ -30,6 +36,12 @@ public static TPosition GetPositionByIdentifier<TPosition>(this IEnumerable<TPos
         public static TPosition GetPositionBySession<TPosition>(this IProcessHolderGroup<TPosition> group, Session session)
             where TPosition : IProcessHolderPosition => GetPosition(group.Positions, t => t.Session?.Id == session.Id);
 
+        /// <summary>
+        /// Get the position by its <see cref="IProcessHolderPosition.Session"/>
+        /// </summary>
+        public static IProcessHolderPosition GetPositionBySession(this IProcessHolderGroup group, Session session)
+            => GetPosition(group.Positions, t => t.Session?.Id == session.Id);
+
         /// <summary>
         /// Get the position by its <see cref="IProcessHolderPosition.Session"/>
         /// </summary>
@@ -42,6 +54,12 @@ public static TPosition GetPositionBySession<TPosition>(this IEnumerable<TPositi
         public static TPosition GetPositionByProcessId<TPosition>(this IProcessHolderGroup<TPosition> group, long processId)
             where TPosition : IProcessHolderPosition => GetPosition(group.Positions, t => t.Process?.Id == processId);
 
+        /// <summary>
+        /// Get the position by its <see cref="IProcessHolderPosition.Process"/>
+        /// </summary>
+        public static IProcessHolderPosition GetPositionByProcessId(this IProcessHolderGroup group, long processId)
+            => GetPosition(group.Positions, t => t.Process?.Id == processId);
+
         /// <summary>
         /// Get the position by its <see cref="IProcessHolderPosition.Process"/>
         /// </summary>
@@ -54,12 +72,40 @@ public static TPosition GetPositionByProcessId<TPosition>(this IEnumerable<TPosi
         public static TPosition GetPositionByActivityId<TPosition>(this IProcessHolderGroup<TPosition> group, long activityId)
             where TPosition : IProcessHolderPosition => GetPosition(group.Positions, t => (t.Session as ActivityStart)?.Activity.Id == activityId);
 
+        /// <summary>
+        /// Get the position by id of the running activity
+        /// </summary>
+        public static IProcessHolderPosition GetPositionByActivityId(this IProcessHolderGroup group, long activityId)
+            => GetPosition(group.Positions, t => (t.Session as ActivityStart)?.Activity.Id == activityId);
+
         /// <summary>
         /// Get the position by id of the running activity
         /// </summary>
         public static TPosition GetPositionByActivityId<TPosition>(this IEnumerable<TPosition> positions, long activityId)
             where TPosition : IProcessHolderPosition => GetPosition(positions, t => (t.Session as ActivityStart)?.Activity.Id == activityId);
 
+        /// <summary>
+        /// Tries to get an empty <see cref="IProcessHolderPosition"/> from the <paramref name="group"/>
+        /// </summary>
+        /// <param name="group">The group to search</param>
+        /// <param name="position">When this method returns, contains the first empty 
+        /// <see cref="IProcessHolderPosition"/>, if any is found; otherwise <c>null</c></param>
+        /// <returns>
+        /// <c>true</c> if an empty <see cref="IProcessHolderPosition"/> was found; otherwise, <c>false</c>.
+        /// </returns>
+        public static bool TryGetEmptyPosition(this IProcessHolderGroup group, out IProcessHolderPosition position)
+        {
+            foreach (var possible in group.Positions)
+            {
+                if (!possible.IsEmpty())
+                    continue;
+                position = possible;
+                return true;
+            }
+            position = default;
+            return false;
+        }
+
         private static TPosition GetPosition<TPosition>(IEnumerable<TPosition> positions, Func<TPosition, bool> filter)
             where TPosition : IProcessHolderPosition => positions.SingleOrDefault(filter);
 
@@ -92,6 +138,30 @@ public static IEnumerable<Session> Attach(this ProcessHolderPosition position)
         public static IEnumerable<Session> Attach(this IEnumerable<ProcessHolderPosition> positions) 
             => positions.SelectMany(p => p.Attach());
 
+        /// <summary>
+        /// Get or create sessions for all <see cref="IProcessHolderGroup.Positions"/> that have a process. 
+        /// This is usually used when attaching to the control system.
+        /// </summary>
+        public static IEnumerable<Session> Attach(this IProcessHolderGroup group)
+        {
+            var sessions = new List<Session>();
+            foreach(var position in group.Positions)
+            {
+                if (position.Session is not null)
+                {
+                    sessions.Add(position.Session);
+                    continue;
+                }
+                    
+                if (position.Process is null)
+                    continue;
+
+                if (position is ProcessHolderPosition php)
+                    sessions.Add(php.StartSession());
+            }
+            return sessions;
+        }
+
         /// <summary>
         /// Get a session if <paramref name="position"/> has one. Otherwise returns an empty enumerable. 
         /// This is usually used when detaching from the control system.
@@ -105,6 +175,12 @@ public static IEnumerable<Session> Detach(this ProcessHolderPosition position)
         public static IEnumerable<Session> Detach(this IEnumerable<ProcessHolderPosition> positions) 
             => positions.Where(p => p.Session != null).Select(p => p.Session);
 
+        /// <summary>
+        /// Create sessions for all positions on the <paramref name="group"/>, that have a process
+        /// </summary>
+        public static IEnumerable<Session> Detach(this IProcessHolderGroup group)
+            => group.Positions.Where(p => p.Session != null).Select(p => p.Session);
+
         #endregion
 
         #region Mounting
@@ -115,6 +191,12 @@ public static IEnumerable<Session> Detach(this IEnumerable<ProcessHolderPosition
         public static void Mount(this IProcessHolderPosition position, IProcess process) 
             => position.Mount(new MountInformation(process, null));
 
+        /// <summary>
+        /// Assign a <paramref name="session"/> to this position
+        /// </summary>
+        public static void Mount(this IProcessHolderPosition position, Session session)
+            => position.Mount(new MountInformation(null, session));
+
         /// <summary>
         /// Assign <paramref name="process"/> and <paramref name="session"/> to this position
         /// </summary>
@@ -123,7 +205,26 @@ public static void Mount(this IProcessHolderPosition position, IProcess process,
 
         #endregion
 
-        #region Has
+        #region Status Checks
+
+        /// <summary>
+        /// Checks if the <paramref name="group"/> has no empty <see cref="IProcessHolderPosition"/>
+        /// </summary>
+        public static bool IsFull(this IProcessHolderGroup group)
+            => group.Positions.All(position => !position.IsEmpty());
+
+        /// <summary>
+        /// Checks if the <paramref name="group"/> has no filled <see cref="IProcessHolderPosition"/>
+        /// </summary>
+        public static bool IsEmpty(this IProcessHolderGroup group)
+            => group.Positions.All(position => position.IsEmpty());
+
+        /// <summary>
+        /// True if the <paramref name="position"/> has neither a <see cref="IProcessHolderPosition.Process"/> nor a 
+        /// <see cref="IProcessHolderPosition.Session"/>; false otherwise.
+        /// </summary>
+        public static bool IsEmpty(this IProcessHolderPosition position)
+            => position.Process is null && position.Session is null;
 
         /// <summary>
         /// Checks if the group holds a process with a finished activity having the matching result
@@ -144,5 +245,33 @@ public static bool HasFinishedActivity(this IProcessHolderPosition holderPositio
         /// </summary>
         public static TTracing Tracing<TTracing>(this IProcessHolderPosition position)
             where TTracing : Tracing, new() => (position.Session as ActivityStart)?.Activity?.TransformTracing<TTracing>();
+
+        /// <summary>
+        /// Updates <see cref="IProcessHolderPosition.Session"/> and <see cref="IProcessHolderPosition.Process"/> by resetting the 
+        /// <paramref name="position"/> and remounting the <paramref name="session"/>. For <see cref="ProcessHolderPosition"/>s 
+        /// a direct update of the session and process is done on the object.
+        /// </summary>
+        /// <param name="position">The position to update</param>
+        /// <param name="session">The updated session on the position</param>
+        /// <exception cref="InvalidOperationException">Thrown if the given <paramref name="session"/> does not match 
+        /// the session on the <paramref name="position"/></exception>
+        public static void Update(this IProcessHolderPosition position, Session session)
+        {
+            if (position.Session.Id != session.Id)
+                throw new InvalidOperationException($"Tried to update the {nameof(Session)} on an " +
+                    $"{nameof(IProcessHolderPosition)} with a different session. Make sure to " +
+                    $"{nameof(IProcessHolderPosition.Reset)} the {nameof(IProcessHolderPosition)} before " +
+                    $"assigning a new {nameof(Session)}");
+
+            if (position is ProcessHolderPosition explicitPosition)
+            {
+                explicitPosition.Session = session;
+                explicitPosition.AssignProcess(session.Process);
+                return;
+            }
+
+            position.Reset();
+            position.Mount(session.Process, session);
+        }
     }
 }
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