diff --git a/edm4hep.yaml b/edm4hep.yaml
index 3f9b326e2..8ef8a2f2d 100644
--- a/edm4hep.yaml
+++ b/edm4hep.yaml
@@ -308,7 +308,8 @@ datatypes:
       - float likelihood     //likelihood of this hypothesis - in a user defined normalization.
     VectorMembers:
       - float parameters     //parameters associated with this hypothesis. Check/set collection parameters ParameterNames_PIDAlgorithmTypeName for decoding the indices.
-
+    OneToOneRelations:
+      - edm4hep::ReconstructedParticle particle // the particle from which this PID has been computed
 
  #------ Cluster
   edm4hep::Cluster: