Index: Ringtoets/Integration/src/Ringtoets.Integration.Plugin/Merge/AssessmentSectionMergeHandler.cs
===================================================================
diff -u -r4b51144b28eeaa6ae0c10b02b2ccabd6bad8ec2d -r2ade7d912e2a4c2dfe475564b02894d4807f3908
--- Ringtoets/Integration/src/Ringtoets.Integration.Plugin/Merge/AssessmentSectionMergeHandler.cs	(.../AssessmentSectionMergeHandler.cs)	(revision 4b51144b28eeaa6ae0c10b02b2ccabd6bad8ec2d)
+++ Ringtoets/Integration/src/Ringtoets.Integration.Plugin/Merge/AssessmentSectionMergeHandler.cs	(.../AssessmentSectionMergeHandler.cs)	(revision 2ade7d912e2a4c2dfe475564b02894d4807f3908)
@@ -80,12 +80,21 @@
             viewCommands.RemoveAllViewsForItem(assessmentSection);
         }
 
-        private void MergeHydraulicBoundaryLocations(AssessmentSection targetAssessmentSection, AssessmentSection sourceAssessmentSection)
+        private static void MergeHydraulicBoundaryLocations(AssessmentSection targetAssessmentSection, AssessmentSection sourceAssessmentSection)
         {
-            for (var i = 0; i < targetAssessmentSection.HydraulicBoundaryDatabase.Locations.Count; i++)
+            MergeHydraulicBoundaryLocationCalculations(targetAssessmentSection.WaterLevelCalculationsForFactorizedSignalingNorm,
+                                                       sourceAssessmentSection.WaterLevelCalculationsForFactorizedSignalingNorm);
+            MergeHydraulicBoundaryLocationCalculations(targetAssessmentSection.WaterLevelCalculationsForSignalingNorm,
+                                                       sourceAssessmentSection.WaterLevelCalculationsForSignalingNorm);
+        }
+
+        private static void MergeHydraulicBoundaryLocationCalculations(IEnumerable<HydraulicBoundaryLocationCalculation> targetCalculations,
+                                                                IEnumerable<HydraulicBoundaryLocationCalculation> sourceCalculations)
+        {
+            for (var i = 0; i < targetCalculations.Count(); i++)
             {
-                HydraulicBoundaryLocationCalculation targetCalculation = targetAssessmentSection.WaterLevelCalculationsForFactorizedSignalingNorm.ElementAt(i);
-                HydraulicBoundaryLocationCalculation sourceCalculation = sourceAssessmentSection.WaterLevelCalculationsForFactorizedSignalingNorm.ElementAt(i);
+                HydraulicBoundaryLocationCalculation targetCalculation = targetCalculations.ElementAt(i);
+                HydraulicBoundaryLocationCalculation sourceCalculation = sourceCalculations.ElementAt(i);
 
                 if (ShouldMerge(targetCalculation, sourceCalculation))
                 {
@@ -95,7 +104,7 @@
             }
         }
 
-        private bool ShouldMerge(HydraulicBoundaryLocationCalculation targetCalculation, HydraulicBoundaryLocationCalculation sourceCalculation)
+        private static bool ShouldMerge(HydraulicBoundaryLocationCalculation targetCalculation, HydraulicBoundaryLocationCalculation sourceCalculation)
         {
             bool targetCalculationHasOutput = targetCalculation.HasOutput;
             bool sourceCalculationHasOutput = sourceCalculation.HasOutput;
Index: Ringtoets/Integration/test/Ringtoets.Integration.Plugin.Test/Merge/AssessmentSectionMergeHandlerTest.cs
===================================================================
diff -u -rda4d48ee078b36b02655374d271a95a9c2b08e93 -r2ade7d912e2a4c2dfe475564b02894d4807f3908
--- Ringtoets/Integration/test/Ringtoets.Integration.Plugin.Test/Merge/AssessmentSectionMergeHandlerTest.cs	(.../AssessmentSectionMergeHandlerTest.cs)	(revision da4d48ee078b36b02655374d271a95a9c2b08e93)
+++ Ringtoets/Integration/test/Ringtoets.Integration.Plugin.Test/Merge/AssessmentSectionMergeHandlerTest.cs	(.../AssessmentSectionMergeHandlerTest.cs)	(revision 2ade7d912e2a4c2dfe475564b02894d4807f3908)
@@ -346,6 +346,8 @@
         {
             yield return new TestCaseData(new Func<AssessmentSection, IEnumerable<HydraulicBoundaryLocationCalculation>>(
                                               section => section.WaterLevelCalculationsForFactorizedSignalingNorm));
+            yield return new TestCaseData(new Func<AssessmentSection, IEnumerable<HydraulicBoundaryLocationCalculation>>(
+                                              section => section.WaterLevelCalculationsForSignalingNorm));
         }
 
         private static AssessmentSection CreateAssessmentSection(TestHydraulicBoundaryLocation[] locations)