diff --git a/Runtime/Scripts/Core/Cluster.cs b/Runtime/Scripts/Core/Cluster.cs
index 75883a0..56133a0 100644
--- a/Runtime/Scripts/Core/Cluster.cs
+++ b/Runtime/Scripts/Core/Cluster.cs
@@ -180,30 +180,61 @@ namespace NanoBrain {
             foreach (NeuronData neuronData in clusterData.neurons) {
                 Neuron receiver = this.GetNeuron(neuronData.name);
                 foreach (SynapseData synapseData in neuronData.synapses) {
+                    // If the synapse points to another cluster
                     if (synapseData.clusterName != this.name) {
                         // Add reference to external cluster
-                        ClusterPrefab extPrefab = Resources.Load(synapseData.clusterName) as ClusterPrefab;
-                        if (extPrefab == null)
-                            Debug.LogError($"Could not find cluster Resource {synapseData.clusterName}");
-                        else {
-                            uint instanceCount = 1;
-                            ExternalClusterData externalClusterData = null;
-                            foreach (ExternalClusterData externalCluster in clusterData.clusters) {
-                                if (externalCluster.clusterName == synapseData.clusterName) {
-                                    instanceCount = externalCluster.instanceCount;
-                                    externalClusterData = externalCluster;
-                                }
-                            }
-                            if (this.nuclei.Find(nucleus => nucleus.name == synapseData.clusterName) is not Cluster extCluster) {
-                                extCluster = new(extPrefab, this, instanceCount);
-                                if (externalClusterData != null)
-                                    extCluster.name = externalClusterData.name;
-                                //extCluster.name = clusterData.name;
-                            }
-                            Neuron extNeuron = extCluster.GetNeuron(synapseData.neuronName);
-                            Debug.Log("Add receiver for external");
+                        // Do we know the external cluster already?
+                        Cluster extCluster = this.GetCluster(synapseData.clusterName);
+                        if (extCluster == null) {
+                            // if not: create new external cluster
+                            Debug.Log("New ext cluster");
+                            ExternalClusterData externalClusterData = clusterData.GetCluster(synapseData.clusterName);
+                            ClusterPrefab extPrefab = Resources.Load(externalClusterData.prefabName) as ClusterPrefab;
+                            extCluster = new(extPrefab, this, instanceCount) {
+                                name = externalClusterData.name
+                            };
+                        }
+                        // Do we have the synapse already?
+                        Neuron extNeuron = extCluster.GetNeuron(synapseData.neuronName);
+                        Synapse synapse = receiver.GetSynapse(extNeuron); //extCluster, synapseData.neuronName);
+                        if (synapse == null) {
+                            Debug.Log("new receiver for external");
+                            // If not: create new synapse
                             extNeuron.AddReceiver(receiver);
                         }
+
+                        //Cluster foundCluster = this.nuclei.Find(nucleus => nucleus is Cluster cluster && cluster.prefab.name == synapseData.clusterName) as Cluster;
+
+
+                        /*
+                                            ClusterPrefab extPrefab = Resources.Load(synapseData.clusterName) as ClusterPrefab;
+                                            if (extPrefab == null)
+                                                Debug.LogError($"Could not find cluster Resource {synapseData.clusterName}");
+                                            else {
+                                                uint instanceCount = 1;
+                                                ExternalClusterData externalClusterData = null;
+                                                foreach (ExternalClusterData externalCluster in clusterData.clusters) {
+                                                    if (externalCluster.prefabName == synapseData.clusterName) {
+                                                        instanceCount = externalCluster.instanceCount;
+                                                        externalClusterData = externalCluster;
+                                                    }
+                                                }
+                                                Nucleus foundNucleus = this.nuclei.Find(nucleus => nucleus is Cluster cluster && cluster.prefab.name == synapseData.clusterName);
+                                                if (foundNucleus is not Cluster extCluster) {
+                                                    Debug.Log("New ext cluster");
+                                                    extCluster = new(extPrefab, this, instanceCount);
+                                                    if (externalClusterData != null)
+                                                        extCluster.name = externalClusterData.name;
+                                                    //extCluster.name = clusterData.name;
+                                                }
+                                                Neuron extNeuron = extCluster.GetNeuron(synapseData.neuronName);
+                                                Synapse synapse = receiver.GetSynapse(extCluster, synapseData.neuronName);
+                                                if (synapse == null) {
+                                                    Debug.Log("Add receiver for external");
+                                                    extNeuron.AddReceiver(receiver);
+                                                }
+                                            }
+                    */
                     }
                     else {
                         Neuron sender = this.GetNeuron(synapseData.neuronName);
@@ -413,7 +444,7 @@ namespace NanoBrain {
                     }
                 }
             }
-            
+
         }
 
         #endregion Init
@@ -951,17 +982,25 @@ namespace NanoBrain {
                 }
             }
         }
+
+        public ExternalClusterData GetCluster(string clusterName) {
+            foreach (ExternalClusterData cluster in this.clusters) {
+                if (cluster.name == clusterName)
+                    return cluster;
+            }
+            return null;
+        }
     }
 
     [Serializable]
     public class ExternalClusterData {
         public string name;
-        public string clusterName;
+        public string prefabName;
         public uint instanceCount;
 
         public ExternalClusterData(Cluster cluster) {
             this.name = cluster.name;
-            this.clusterName = cluster.prefab.name;
+            this.prefabName = cluster.prefab.name;
             this.instanceCount = (uint)cluster.instanceCount;
         }
     }
diff --git a/Runtime/Scripts/Core/Neuron.cs b/Runtime/Scripts/Core/Neuron.cs
index 7261f2c..24aea7d 100644
--- a/Runtime/Scripts/Core/Neuron.cs
+++ b/Runtime/Scripts/Core/Neuron.cs
@@ -95,6 +95,12 @@ namespace NanoBrain {
 
             return this.GetSynapse(sender);
         }
+        public Synapse GetSynapse(Cluster cluster, string senderNeuronName) {
+            Neuron sender = cluster.GetNeuron(senderNeuronName);
+            if (sender == null)
+                return null;
+            return this.GetSynapse(sender);
+        }
 
         /// <summary>
         /// Remove a synapse from a Nucleus
diff --git a/Runtime/Scripts/Core/Synapse.cs b/Runtime/Scripts/Core/Synapse.cs
index d92af2f..a791a74 100644
--- a/Runtime/Scripts/Core/Synapse.cs
+++ b/Runtime/Scripts/Core/Synapse.cs
@@ -144,10 +144,11 @@ namespace NanoBrain {
         public bool trainable;
 
         public SynapseData(Synapse synapse) {
-            if (synapse.neuron.parent.prefab != null)
-                this.clusterName = synapse.neuron.parent.prefab.name;
-            else
-                this.clusterName = synapse.neuron.parent.name;
+            // if (synapse.neuron.parent.prefab != null)
+            //     this.clusterName = synapse.neuron.parent.prefab.name;
+            // else
+            //     this.clusterName = synapse.neuron.parent.name;
+            this.clusterName = synapse.neuron.parent.name;
             this.neuronName = synapse.neuron.name;
             this.weight = synapse.weight;
             this.trainable = synapse.trainable;