Index: Ringtoets/ClosingStructures/test/Ringtoets.ClosingStructures.Plugin.Test/TreeNodeInfos/ClosingStructuresCalculationGroupContextTreeNodeInfoTest.cs
===================================================================
diff -u -r5f489223b4d730eec42acd55533dd012d10dd1ca -r5bca160555d6a573d0defcea46dd4e60e16cc274
--- Ringtoets/ClosingStructures/test/Ringtoets.ClosingStructures.Plugin.Test/TreeNodeInfos/ClosingStructuresCalculationGroupContextTreeNodeInfoTest.cs	(.../ClosingStructuresCalculationGroupContextTreeNodeInfoTest.cs)	(revision 5f489223b4d730eec42acd55533dd012d10dd1ca)
+++ Ringtoets/ClosingStructures/test/Ringtoets.ClosingStructures.Plugin.Test/TreeNodeInfos/ClosingStructuresCalculationGroupContextTreeNodeInfoTest.cs	(.../ClosingStructuresCalculationGroupContextTreeNodeInfoTest.cs)	(revision 5bca160555d6a573d0defcea46dd4e60e16cc274)
@@ -885,12 +885,22 @@
                 ClosingStructure structure1 = new TestClosingStructure("Structure 1");
                 ClosingStructure structure2 = new TestClosingStructure("Structure 2");
 
+                var existingCalculationGroup = new CalculationGroup();
+                var existingCalculation = new StructuresCalculation<ClosingStructuresInput>();
                 var failureMechanism = new ClosingStructuresFailureMechanism
                 {
                     ClosingStructures =
                     {
                         structure1,
                         structure2
+                    },
+                    CalculationsGroup =
+                    {
+                        Children =
+                        {
+                            existingCalculationGroup,
+                            existingCalculation
+                        }
                     }
                 };
 
@@ -925,9 +935,12 @@
                     contextMenu.Items[contextMenuGenerateCalculationsIndexRootGroup].PerformClick();
 
                     // Then
-                    var closingStructuresCalculations = failureMechanism.Calculations.OfType<StructuresCalculation<ClosingStructuresInput>>().ToArray();
-                    Assert.AreEqual(1, closingStructuresCalculations.Length);
-                    Assert.AreSame(structure1, closingStructuresCalculations[0].InputParameters.Structure);
+                    Assert.AreEqual(3, failureMechanism.CalculationsGroup.Children.Count);
+                    Assert.AreSame(existingCalculationGroup, failureMechanism.CalculationsGroup.Children[0]);
+                    Assert.AreSame(existingCalculation, failureMechanism.CalculationsGroup.Children[1]);
+                    var generatedCalculation = failureMechanism.CalculationsGroup.Children[2] as StructuresCalculation<ClosingStructuresInput>;
+                    Assert.IsNotNull(generatedCalculation);
+                    Assert.AreSame(structure1, generatedCalculation.InputParameters.Structure);
                 }
             }
         }
Index: Ringtoets/GrassCoverErosionInwards/test/Ringtoets.GrassCoverErosionInwards.Plugin.Test/TreeNodeInfos/GrassCoverErosionInwardsCalculationGroupContextTreeNodeInfoTest.cs
===================================================================
diff -u -r9448c9f34da890e184722d00c3f8b4f765a246b0 -r5bca160555d6a573d0defcea46dd4e60e16cc274
--- Ringtoets/GrassCoverErosionInwards/test/Ringtoets.GrassCoverErosionInwards.Plugin.Test/TreeNodeInfos/GrassCoverErosionInwardsCalculationGroupContextTreeNodeInfoTest.cs	(.../GrassCoverErosionInwardsCalculationGroupContextTreeNodeInfoTest.cs)	(revision 9448c9f34da890e184722d00c3f8b4f765a246b0)
+++ Ringtoets/GrassCoverErosionInwards/test/Ringtoets.GrassCoverErosionInwards.Plugin.Test/TreeNodeInfos/GrassCoverErosionInwardsCalculationGroupContextTreeNodeInfoTest.cs	(.../GrassCoverErosionInwardsCalculationGroupContextTreeNodeInfoTest.cs)	(revision 5bca160555d6a573d0defcea46dd4e60e16cc274)
@@ -1100,12 +1100,22 @@
                 DikeProfile dikeProfile1 = new TestDikeProfile("Dike profile 1");
                 DikeProfile dikeProfile2 = new TestDikeProfile("Dike profile 2");
 
+                var existingCalculationGroup = new CalculationGroup();
+                var existingCalculation = new GrassCoverErosionInwardsCalculation();
                 var failureMechanism = new GrassCoverErosionInwardsFailureMechanism
                 {
                     DikeProfiles =
                     {
                         dikeProfile1,
                         dikeProfile2
+                    },
+                    CalculationsGroup =
+                    {
+                        Children =
+                        {
+                            existingCalculationGroup,
+                            existingCalculation
+                        }
                     }
                 };
 
@@ -1140,9 +1150,12 @@
                     contextMenu.Items[contextMenuGenerateCalculationsIndexRootGroup].PerformClick();
 
                     // Then
-                    var grassCoverErosionInwardsCalculations = failureMechanism.Calculations.OfType<GrassCoverErosionInwardsCalculation>().ToArray();
-                    Assert.AreEqual(1, grassCoverErosionInwardsCalculations.Length);
-                    Assert.AreSame(dikeProfile1, grassCoverErosionInwardsCalculations[0].InputParameters.DikeProfile);
+                    Assert.AreEqual(3, failureMechanism.CalculationsGroup.Children.Count);
+                    Assert.AreSame(existingCalculationGroup, failureMechanism.CalculationsGroup.Children[0]);
+                    Assert.AreSame(existingCalculation, failureMechanism.CalculationsGroup.Children[1]);
+                    var generatedCalculation = failureMechanism.CalculationsGroup.Children[2] as GrassCoverErosionInwardsCalculation;
+                    Assert.IsNotNull(generatedCalculation);
+                    Assert.AreSame(dikeProfile1, generatedCalculation.InputParameters.DikeProfile);
                 }
             }
         }
Index: Ringtoets/HeightStructures/test/Ringtoets.HeightStructures.Plugin.Test/TreeNodeInfos/HeightStructuresCalculationGroupContextTreeNodeInfoTest.cs
===================================================================
diff -u -rb25389d952b8ac86e61c5e822124b2c250ae3e55 -r5bca160555d6a573d0defcea46dd4e60e16cc274
--- Ringtoets/HeightStructures/test/Ringtoets.HeightStructures.Plugin.Test/TreeNodeInfos/HeightStructuresCalculationGroupContextTreeNodeInfoTest.cs	(.../HeightStructuresCalculationGroupContextTreeNodeInfoTest.cs)	(revision b25389d952b8ac86e61c5e822124b2c250ae3e55)
+++ Ringtoets/HeightStructures/test/Ringtoets.HeightStructures.Plugin.Test/TreeNodeInfos/HeightStructuresCalculationGroupContextTreeNodeInfoTest.cs	(.../HeightStructuresCalculationGroupContextTreeNodeInfoTest.cs)	(revision 5bca160555d6a573d0defcea46dd4e60e16cc274)
@@ -1039,12 +1039,22 @@
                 HeightStructure structure1 = new TestHeightStructure("Structure 1");
                 HeightStructure structure2 = new TestHeightStructure("Structure 2");
 
+                var existingCalculationGroup = new CalculationGroup();
+                var existingCalculation = new StructuresCalculation<HeightStructuresInput>();
                 var failureMechanism = new HeightStructuresFailureMechanism
                 {
                     HeightStructures =
                     {
                         structure1,
                         structure2
+                    },
+                    CalculationsGroup =
+                    {
+                        Children =
+                        {
+                            existingCalculationGroup,
+                            existingCalculation
+                        }
                     }
                 };
 
@@ -1079,9 +1089,12 @@
                     contextMenu.Items[contextMenuGenerateCalculationsIndexRootGroup].PerformClick();
 
                     // Then
-                    var heightStructuresCalculations = failureMechanism.Calculations.OfType<StructuresCalculation<HeightStructuresInput>>().ToArray();
-                    Assert.AreEqual(1, heightStructuresCalculations.Length);
-                    Assert.AreSame(structure1, heightStructuresCalculations[0].InputParameters.Structure);
+                    Assert.AreEqual(3, failureMechanism.CalculationsGroup.Children.Count);
+                    Assert.AreSame(existingCalculationGroup, failureMechanism.CalculationsGroup.Children[0]);
+                    Assert.AreSame(existingCalculation, failureMechanism.CalculationsGroup.Children[1]);
+                    var generatedCalculation = failureMechanism.CalculationsGroup.Children[2] as StructuresCalculation<HeightStructuresInput>;
+                    Assert.IsNotNull(generatedCalculation);
+                    Assert.AreSame(structure1, generatedCalculation.InputParameters.Structure);
                 }
             }
         }
Index: Ringtoets/StabilityPointStructures/test/Ringtoets.StabilityPointStructures.Plugin.Test/TreeNodeInfos/StabilityPointStructuresCalculationGroupContextTreeNodeInfoTest.cs
===================================================================
diff -u -r59d8943b166f40b1d8b3595b43b2a524e719b2ef -r5bca160555d6a573d0defcea46dd4e60e16cc274
--- Ringtoets/StabilityPointStructures/test/Ringtoets.StabilityPointStructures.Plugin.Test/TreeNodeInfos/StabilityPointStructuresCalculationGroupContextTreeNodeInfoTest.cs	(.../StabilityPointStructuresCalculationGroupContextTreeNodeInfoTest.cs)	(revision 59d8943b166f40b1d8b3595b43b2a524e719b2ef)
+++ Ringtoets/StabilityPointStructures/test/Ringtoets.StabilityPointStructures.Plugin.Test/TreeNodeInfos/StabilityPointStructuresCalculationGroupContextTreeNodeInfoTest.cs	(.../StabilityPointStructuresCalculationGroupContextTreeNodeInfoTest.cs)	(revision 5bca160555d6a573d0defcea46dd4e60e16cc274)
@@ -875,12 +875,22 @@
                 StabilityPointStructure structure1 = new TestStabilityPointStructure("Structure 1");
                 StabilityPointStructure structure2 = new TestStabilityPointStructure("Structure 2");
 
+                var existingCalculationGroup = new CalculationGroup();
+                var existingCalculation = new StructuresCalculation<StabilityPointStructuresInput>();
                 var failureMechanism = new StabilityPointStructuresFailureMechanism
                 {
                     StabilityPointStructures =
                     {
                         structure1,
                         structure2
+                    },
+                    CalculationsGroup =
+                    {
+                        Children =
+                        {
+                            existingCalculationGroup,
+                            existingCalculation
+                        }
                     }
                 };
 
@@ -915,9 +925,12 @@
                     contextMenu.Items[contextMenuGenerateCalculationsIndexRootGroup].PerformClick();
 
                     // Then
-                    StructuresCalculation<StabilityPointStructuresInput>[] stabilityPointStructuresCalculations = failureMechanism.Calculations.OfType<StructuresCalculation<StabilityPointStructuresInput>>().ToArray();
-                    Assert.AreEqual(1, stabilityPointStructuresCalculations.Length);
-                    Assert.AreSame(structure1, stabilityPointStructuresCalculations[0].InputParameters.Structure);
+                    Assert.AreEqual(3, failureMechanism.CalculationsGroup.Children.Count);
+                    Assert.AreSame(existingCalculationGroup, failureMechanism.CalculationsGroup.Children[0]);
+                    Assert.AreSame(existingCalculation, failureMechanism.CalculationsGroup.Children[1]);
+                    var generatedCalculation = failureMechanism.CalculationsGroup.Children[2] as StructuresCalculation<StabilityPointStructuresInput>;
+                    Assert.IsNotNull(generatedCalculation);
+                    Assert.AreSame(structure1, generatedCalculation.InputParameters.Structure);
                 }
             }
         }