diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/er/entity/EntityManagement.java b/src/main/java/org/gcube/informationsystem/resourceregistry/er/entity/EntityManagement.java
index c159a40..2f3e383 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/er/entity/EntityManagement.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/er/entity/EntityManagement.java
@@ -67,10 +67,27 @@ public abstract class EntityManagement<E extends Entity> extends
 		RelationManagement relationManagement = relationManagements.get(id);
 		if(relationManagement==null) {
 			relationManagement = ERManagementUtility.getRelationManagement(orientGraph, edge);
+			relationManagements.put(id, relationManagement);
 		}
 		return relationManagement;
 	}
 
+	protected void addToRelationManagement(@SuppressWarnings("rawtypes") RelationManagement relationManagement) throws ResourceRegistryException {
+		Element elem = relationManagement.getElement();
+		String id = elem.getId().toString();
+		if(relationManagements.get(id)!=relationManagement) {
+			StringBuilder errorMessage = new StringBuilder();
+			errorMessage.append("Two different instance of ");
+			errorMessage.append(relationManagement.getClass().getSimpleName());
+			errorMessage.append(" point to the same ");
+			errorMessage.append(elem.getClass().getSimpleName());
+			errorMessage.append(". ");
+			errorMessage.append(Utility.SHOULD_NOT_OCCUR_ERROR_MESSAGE);
+			throw new ResourceRegistryException(errorMessage.toString());
+		}
+		relationManagements.put(id, relationManagement);
+	}
+	
 	protected EntityManagement(AccessType accessType, OrientGraph orientGraph) {
 		this(accessType);
 		this.orientGraph = orientGraph;
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/er/entity/ResourceManagement.java b/src/main/java/org/gcube/informationsystem/resourceregistry/er/entity/ResourceManagement.java
index 9ae9bbd..6a98faf 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/er/entity/ResourceManagement.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/er/entity/ResourceManagement.java
@@ -84,9 +84,19 @@ public class ResourceManagement extends EntityManagement<Resource> {
 		
 		Iterable<Edge> edges = getElement().getEdges(Direction.OUT);
 		for (Edge edge : edges) {
+			
 			@SuppressWarnings("rawtypes")
-			RelationManagement relationManagement = ERManagementUtility.getRelationManagement(orientGraph, edge);
-			relationManagement.setSourceEntityManagement(this);
+			RelationManagement relationManagement = getRelationManagement(edge);
+			if(relationManagement.getSourceEntityManagement()==null) {
+				relationManagement.setSourceEntityManagement(this);
+			}else if(relationManagement.getSourceEntityManagement()!=null) {
+				StringBuilder errorMessage = new StringBuilder();
+				errorMessage.append("SourceEntityManagement for ");
+				errorMessage.append(relationManagement.getClass().getSimpleName());
+				errorMessage.append(" is not the one expected. ");
+				errorMessage.append(Utility.SHOULD_NOT_OCCUR_ERROR_MESSAGE);
+				throw new ResourceRegistryException(errorMessage.toString());
+			}
 			
 			if (relationManagement instanceof ConsistsOfManagement) {
 				try {
@@ -106,8 +116,7 @@ public class ResourceManagement extends EntityManagement<Resource> {
 			 * by default as design choice and not because forget
 			 * 
 			 * else if(orientEdgeType.isSubClassOf(IsRelatedTo.NAME)){
-			 * 	 JSONObject isRelatedTo = relationManagement
-						.serializeAsJson();
+			 * 	 JSONObject isRelatedTo = relationManagement.serializeAsJson(true, true);
 			 * 	 sourceResource = addIsRelatedTo(sourceResource, isRelatedTo);
 			 * }
 			 */
@@ -140,6 +149,7 @@ public class ResourceManagement extends EntityManagement<Resource> {
 				com.setJSON(consistOfJsonNode);
 				com.setSourceEntityManagement(this);
 				com.internalCreate();
+				addToRelationManagement(com);
 			}
 		}
 
@@ -152,6 +162,7 @@ public class ResourceManagement extends EntityManagement<Resource> {
 				irtm.setJSON(relationJsonNode);
 				irtm.setSourceEntityManagement(this);
 				irtm.internalCreate();
+				addToRelationManagement(irtm);
 			}
 		}
 
@@ -170,6 +181,7 @@ public class ResourceManagement extends EntityManagement<Resource> {
 				ConsistsOfManagement com = new ConsistsOfManagement(orientGraph);
 				com.setJSON(relationJsonNode);
 				com.internalCreateOrUdate();
+				addToRelationManagement(com);
 			}
 		}
 
@@ -181,6 +193,7 @@ public class ResourceManagement extends EntityManagement<Resource> {
 						orientGraph);
 				irtm.setJSON(relationJsonNode);
 				irtm.internalUpdate();
+				addToRelationManagement(irtm);
 			}
 		}
 
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/er/relation/RelationManagement.java b/src/main/java/org/gcube/informationsystem/resourceregistry/er/relation/RelationManagement.java
index 28ba472..b29576f 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/er/relation/RelationManagement.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/er/relation/RelationManagement.java
@@ -3,7 +3,6 @@
  */
 package org.gcube.informationsystem.resourceregistry.er.relation;
 
-import java.io.StringWriter;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
@@ -92,7 +91,7 @@ public abstract class RelationManagement<R extends Relation, S extends EntityMan
 	}
 
 	@SuppressWarnings("unchecked")
-	protected S getSourceEntityManagement() throws ResourceRegistryException {
+	public S getSourceEntityManagement() throws ResourceRegistryException {
 		if (sourceEntityManagement == null) {
 			Vertex source = getElement().getVertex(Direction.OUT);
 			sourceEntityManagement = newSourceEntityManagement();
@@ -219,7 +218,7 @@ public abstract class RelationManagement<R extends Relation, S extends EntityMan
 			try {
 				targetEntityManagement.setJSON(jsonNode.get(Relation.TARGET_PROPERTY));
 			} catch (SchemaException e) {
-				StringWriter errorMessage = new StringWriter();
+				StringBuilder errorMessage = new StringBuilder();
 				errorMessage.append("A ");
 				errorMessage.append(erType);
 				errorMessage.append(" can be only created beetween ");
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/utils/Utility.java b/src/main/java/org/gcube/informationsystem/resourceregistry/utils/Utility.java
index 93b8709..e787282 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/utils/Utility.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/utils/Utility.java
@@ -41,6 +41,8 @@ public class Utility {
 
 	private static final Logger logger = LoggerFactory.getLogger(Utility.class);
 
+	public static final String SHOULD_NOT_OCCUR_ERROR_MESSAGE = "This is really strange and should not occur. Please contact the system administrator";
+	
 	public static JSONObject toJsonObject(OrientElement element, boolean raw)
 			throws ResourceRegistryException {
 		try {