diff --git a/datamodels/2.x/itop-virtualization-mgmt/datamodel.itop-virtualization-mgmt.xml b/datamodels/2.x/itop-virtualization-mgmt/datamodel.itop-virtualization-mgmt.xml
index e3c9160fac..ad1a02b882 100644
--- a/datamodels/2.x/itop-virtualization-mgmt/datamodel.itop-virtualization-mgmt.xml
+++ b/datamodels/2.x/itop-virtualization-mgmt/datamodel.itop-virtualization-mgmt.xml
@@ -901,11 +901,11 @@
         </list>
       </presentation>
     </class>
-    <class id="Server" _delta="merge">
+    <class id="Server">
       <relations>
         <relation id="impacts">
           <neighbours>
-            <neighbour id="hypervisor">
+            <neighbour id="hypervisor" _delta="define">
               <query_down>SELECT Hypervisor AS o WHERE o.server_id = :this-&gt;id</query_down>
               <query_up>SELECT Server AS o WHERE o.id = :this-&gt;server_id</query_up>
             </neighbour>