Add group ID

com.unity.ml-agents/Editor/BehaviorParametersEditor.cs

             needPolicyUpdate = needPolicyUpdate || EditorGUI.EndChangeCheck();
 
             EditorGUILayout.PropertyField(so.FindProperty("TeamId"));
+            EditorGUILayout.PropertyField(so.FindProperty("GroupId"));
             EditorGUI.BeginDisabledGroup(!EditorUtilities.CanUpdateModelProperties());
             {
                 EditorGUILayout.PropertyField(so.FindProperty("m_UseChildSensors"), true);

com.unity.ml-agents/Runtime/Policies/BehaviorParameters.cs

         /// </summary>
         [HideInInspector, SerializeField, FormerlySerializedAs("m_TeamID")]
         public int TeamId;
+
+        /// <summary>
+        /// The group ID for this behavior.
+        /// </summary>
+        [HideInInspector, SerializeField]
+        [Tooltip("Assign the same Group ID to all Agents in the same Area.")]
+        public int GroupId;
         // TODO properties here instead of Agent
 
         [FormerlySerializedAs("m_useChildSensors")]
         /// </summary>
         public string FullyQualifiedBehaviorName
         {
-            get { return m_BehaviorName + "?team=" + TeamId; }
+            get { return m_BehaviorName + "?team=" + TeamId + "&group=" + GroupId; }
         }
 
         internal IPolicy GeneratePolicy(ActionSpec actionSpec, HeuristicPolicy.ActionGenerator heuristic)

ml-agents/mlagents/trainers/behavior_id_utils.py

     behavior_id: str
     brain_name: str
     team_id: int
+    group_id: int
-        Parses a name_behavior_id of the form name?team=0
+        Parses a name_behavior_id of the form name?team=0&group=0
-
+        group_id: int = 0
+        if "group" in ids:
+            group_id = int(ids["group"][0])
-            behavior_id=name_behavior_id, brain_name=name, team_id=team_id
+            behavior_id=name_behavior_id,
+            brain_name=name,
+            team_id=team_id,
+            group_id=group_id,
         )