Index: Ringtoets/ClosingStructures/src/Ringtoets.ClosingStructures.Forms/PresentationObjects/ClosingStructuresCalculationGroupContext.cs
===================================================================
diff -u -rf0792e734ef5296f2ffaae2ad36619a05d5bd9e3 -r2f2f5862ef2f51e6102511cb6c6de57fbaabe554
--- Ringtoets/ClosingStructures/src/Ringtoets.ClosingStructures.Forms/PresentationObjects/ClosingStructuresCalculationGroupContext.cs	(.../ClosingStructuresCalculationGroupContext.cs)	(revision f0792e734ef5296f2ffaae2ad36619a05d5bd9e3)
+++ Ringtoets/ClosingStructures/src/Ringtoets.ClosingStructures.Forms/PresentationObjects/ClosingStructuresCalculationGroupContext.cs	(.../ClosingStructuresCalculationGroupContext.cs)	(revision 2f2f5862ef2f51e6102511cb6c6de57fbaabe554)
@@ -92,7 +92,7 @@
 
         public override int GetHashCode()
         {
-            return base.GetHashCode() ^ Parent.GetHashCode();
+            return base.GetHashCode() ^ Parent?.GetHashCode() ?? 0;
         }
     }
 }
\ No newline at end of file
Index: Ringtoets/GrassCoverErosionInwards/src/Ringtoets.GrassCoverErosionInwards.Forms/PresentationObjects/GrassCoverErosionInwardsCalculationGroupContext.cs
===================================================================
diff -u -rf0792e734ef5296f2ffaae2ad36619a05d5bd9e3 -r2f2f5862ef2f51e6102511cb6c6de57fbaabe554
--- Ringtoets/GrassCoverErosionInwards/src/Ringtoets.GrassCoverErosionInwards.Forms/PresentationObjects/GrassCoverErosionInwardsCalculationGroupContext.cs	(.../GrassCoverErosionInwardsCalculationGroupContext.cs)	(revision f0792e734ef5296f2ffaae2ad36619a05d5bd9e3)
+++ Ringtoets/GrassCoverErosionInwards/src/Ringtoets.GrassCoverErosionInwards.Forms/PresentationObjects/GrassCoverErosionInwardsCalculationGroupContext.cs	(.../GrassCoverErosionInwardsCalculationGroupContext.cs)	(revision 2f2f5862ef2f51e6102511cb6c6de57fbaabe554)
@@ -68,7 +68,7 @@
 
         public override int GetHashCode()
         {
-            return base.GetHashCode() ^ Parent.GetHashCode();
+            return base.GetHashCode() ^ Parent?.GetHashCode() ?? 0;
         }
     }
 }
\ No newline at end of file
Index: Ringtoets/GrassCoverErosionOutwards/src/Ringtoets.GrassCoverErosionOutwards.Forms/PresentationObjects/GrassCoverErosionOutwardsWaveConditionsCalculationGroupContext.cs
===================================================================
diff -u -rf0792e734ef5296f2ffaae2ad36619a05d5bd9e3 -r2f2f5862ef2f51e6102511cb6c6de57fbaabe554
--- Ringtoets/GrassCoverErosionOutwards/src/Ringtoets.GrassCoverErosionOutwards.Forms/PresentationObjects/GrassCoverErosionOutwardsWaveConditionsCalculationGroupContext.cs	(.../GrassCoverErosionOutwardsWaveConditionsCalculationGroupContext.cs)	(revision f0792e734ef5296f2ffaae2ad36619a05d5bd9e3)
+++ Ringtoets/GrassCoverErosionOutwards/src/Ringtoets.GrassCoverErosionOutwards.Forms/PresentationObjects/GrassCoverErosionOutwardsWaveConditionsCalculationGroupContext.cs	(.../GrassCoverErosionOutwardsWaveConditionsCalculationGroupContext.cs)	(revision 2f2f5862ef2f51e6102511cb6c6de57fbaabe554)
@@ -67,7 +67,7 @@
 
         public override int GetHashCode()
         {
-            return base.GetHashCode() ^ Parent.GetHashCode();
+            return base.GetHashCode() ^ Parent?.GetHashCode() ?? 0;
         }
     }
 }
\ No newline at end of file
Index: Ringtoets/HeightStructures/src/Ringtoets.HeightStructures.Forms/PresentationObjects/HeightStructuresCalculationGroupContext.cs
===================================================================
diff -u -rf0792e734ef5296f2ffaae2ad36619a05d5bd9e3 -r2f2f5862ef2f51e6102511cb6c6de57fbaabe554
--- Ringtoets/HeightStructures/src/Ringtoets.HeightStructures.Forms/PresentationObjects/HeightStructuresCalculationGroupContext.cs	(.../HeightStructuresCalculationGroupContext.cs)	(revision f0792e734ef5296f2ffaae2ad36619a05d5bd9e3)
+++ Ringtoets/HeightStructures/src/Ringtoets.HeightStructures.Forms/PresentationObjects/HeightStructuresCalculationGroupContext.cs	(.../HeightStructuresCalculationGroupContext.cs)	(revision 2f2f5862ef2f51e6102511cb6c6de57fbaabe554)
@@ -92,7 +92,7 @@
 
         public override int GetHashCode()
         {
-            return base.GetHashCode() ^ Parent.GetHashCode();
+            return base.GetHashCode() ^ Parent?.GetHashCode() ?? 0;
         }
     }
 }
\ No newline at end of file
Index: Ringtoets/Integration/test/Ringtoets.Integration.Plugin.Test/TreeNodeInfos/HydraulicBoundaryDatabaseContextTreeNodeInfoTest.cs
===================================================================
diff -u -r9d5f42a34e94425c8a21ba8fcf0e33b41b78ff69 -r2f2f5862ef2f51e6102511cb6c6de57fbaabe554
--- Ringtoets/Integration/test/Ringtoets.Integration.Plugin.Test/TreeNodeInfos/HydraulicBoundaryDatabaseContextTreeNodeInfoTest.cs	(.../HydraulicBoundaryDatabaseContextTreeNodeInfoTest.cs)	(revision 9d5f42a34e94425c8a21ba8fcf0e33b41b78ff69)
+++ Ringtoets/Integration/test/Ringtoets.Integration.Plugin.Test/TreeNodeInfos/HydraulicBoundaryDatabaseContextTreeNodeInfoTest.cs	(.../HydraulicBoundaryDatabaseContextTreeNodeInfoTest.cs)	(revision 2f2f5862ef2f51e6102511cb6c6de57fbaabe554)
@@ -260,11 +260,14 @@
 
                 // Assert
                 Assert.AreEqual(2, objects.Length);
+
                 var designWaterLevelLocationsGroupContext = (DesignWaterLevelLocationsGroupContext) objects[0];
                 Assert.AreSame(assessmentSection.HydraulicBoundaryDatabase.Locations, designWaterLevelLocationsGroupContext.WrappedData);
+                Assert.AreSame(assessmentSection, designWaterLevelLocationsGroupContext.AssessmentSection);
 
                 var waveHeightLocationsGroupContext = (WaveHeightLocationsGroupContext) objects[1];
                 Assert.AreSame(assessmentSection.HydraulicBoundaryDatabase.Locations, waveHeightLocationsGroupContext.WrappedData);
+                Assert.AreSame(assessmentSection, waveHeightLocationsGroupContext.AssessmentSection);
             }
         }
 
Index: Ringtoets/StabilityPointStructures/src/Ringtoets.StabilityPointStructures.Forms/PresentationObjects/StabilityPointStructuresCalculationGroupContext.cs
===================================================================
diff -u -r3ddd2dfb07fb310dd90d5aac12e213d188c87a9a -r2f2f5862ef2f51e6102511cb6c6de57fbaabe554
--- Ringtoets/StabilityPointStructures/src/Ringtoets.StabilityPointStructures.Forms/PresentationObjects/StabilityPointStructuresCalculationGroupContext.cs	(.../StabilityPointStructuresCalculationGroupContext.cs)	(revision 3ddd2dfb07fb310dd90d5aac12e213d188c87a9a)
+++ Ringtoets/StabilityPointStructures/src/Ringtoets.StabilityPointStructures.Forms/PresentationObjects/StabilityPointStructuresCalculationGroupContext.cs	(.../StabilityPointStructuresCalculationGroupContext.cs)	(revision 2f2f5862ef2f51e6102511cb6c6de57fbaabe554)
@@ -92,7 +92,7 @@
 
         public override int GetHashCode()
         {
-            return base.GetHashCode() ^ Parent.GetHashCode();
+            return base.GetHashCode() ^ Parent?.GetHashCode() ?? 0;
         }
     }
 }
\ No newline at end of file
Index: Ringtoets/StabilityStoneCover/src/Ringtoets.StabilityStoneCover.Forms/PresentationObjects/StabilityStoneCoverWaveConditionsCalculationGroupContext.cs
===================================================================
diff -u -rf0792e734ef5296f2ffaae2ad36619a05d5bd9e3 -r2f2f5862ef2f51e6102511cb6c6de57fbaabe554
--- Ringtoets/StabilityStoneCover/src/Ringtoets.StabilityStoneCover.Forms/PresentationObjects/StabilityStoneCoverWaveConditionsCalculationGroupContext.cs	(.../StabilityStoneCoverWaveConditionsCalculationGroupContext.cs)	(revision f0792e734ef5296f2ffaae2ad36619a05d5bd9e3)
+++ Ringtoets/StabilityStoneCover/src/Ringtoets.StabilityStoneCover.Forms/PresentationObjects/StabilityStoneCoverWaveConditionsCalculationGroupContext.cs	(.../StabilityStoneCoverWaveConditionsCalculationGroupContext.cs)	(revision 2f2f5862ef2f51e6102511cb6c6de57fbaabe554)
@@ -67,7 +67,7 @@
 
         public override int GetHashCode()
         {
-            return base.GetHashCode() ^ Parent.GetHashCode();
+            return base.GetHashCode() ^ Parent?.GetHashCode() ?? 0;
         }
     }
 }
\ No newline at end of file
Index: Ringtoets/WaveImpactAsphaltCover/src/Ringtoets.WaveImpactAsphaltCover.Forms/PresentationObjects/WaveImpactAsphaltCoverCalculationGroupContext.cs
===================================================================
diff -u -rf0792e734ef5296f2ffaae2ad36619a05d5bd9e3 -r2f2f5862ef2f51e6102511cb6c6de57fbaabe554
--- Ringtoets/WaveImpactAsphaltCover/src/Ringtoets.WaveImpactAsphaltCover.Forms/PresentationObjects/WaveImpactAsphaltCoverCalculationGroupContext.cs	(.../WaveImpactAsphaltCoverCalculationGroupContext.cs)	(revision f0792e734ef5296f2ffaae2ad36619a05d5bd9e3)
+++ Ringtoets/WaveImpactAsphaltCover/src/Ringtoets.WaveImpactAsphaltCover.Forms/PresentationObjects/WaveImpactAsphaltCoverCalculationGroupContext.cs	(.../WaveImpactAsphaltCoverCalculationGroupContext.cs)	(revision 2f2f5862ef2f51e6102511cb6c6de57fbaabe554)
@@ -68,7 +68,7 @@
 
         public override int GetHashCode()
         {
-            return base.GetHashCode() ^ Parent.GetHashCode();
+            return base.GetHashCode() ^ Parent?.GetHashCode() ?? 0;
         }
     }
 }
\ No newline at end of file