Index: DamClients/DamUI/trunk/src/DamClientsLibrary/Deltares.Dam.Data/IO/BackwardCompatibility.cs
===================================================================
diff -u -r4070 -r4511
--- DamClients/DamUI/trunk/src/DamClientsLibrary/Deltares.Dam.Data/IO/BackwardCompatibility.cs	(.../BackwardCompatibility.cs)	(revision 4070)
+++ DamClients/DamUI/trunk/src/DamClientsLibrary/Deltares.Dam.Data/IO/BackwardCompatibility.cs	(.../BackwardCompatibility.cs)	(revision 4511)
@@ -134,15 +134,21 @@
     {
         foreach (Scenario scenario in location.Scenarios)
         {
-            scenario.HeadPl3 = value;
+            if (scenario.HeadPl3 == null || value != null)
+            {
+                scenario.HeadPl3 = value;
+            }
         }
     }
 
     private static void UpdateHeadPl4(Location location, double? value)
     {
         foreach (Scenario scenario in location.Scenarios)
         {
-            scenario.HeadPl4 = value;
+            if (scenario.HeadPl4 == null || value != null)
+            {
+                scenario.HeadPl4 = value;
+            }
         }
     }