Index: Ringtoets/Integration/src/Ringtoets.Integration.Plugin/AssessmentSectionMerger.cs
===================================================================
diff -u -r36fb70b04307e0805488e2862cd94b1820f6bb1e -r7fad62a843a5b8cd970b900800b851581e49476a
--- Ringtoets/Integration/src/Ringtoets.Integration.Plugin/AssessmentSectionMerger.cs	(.../AssessmentSectionMerger.cs)	(revision 36fb70b04307e0805488e2862cd94b1820f6bb1e)
+++ Ringtoets/Integration/src/Ringtoets.Integration.Plugin/AssessmentSectionMerger.cs	(.../AssessmentSectionMerger.cs)	(revision 7fad62a843a5b8cd970b900800b851581e49476a)
@@ -27,6 +27,7 @@
 using Ringtoets.Integration.Data;
 using Ringtoets.Integration.Data.Merge;
 using Ringtoets.Integration.Forms.Merge;
+using Ringtoets.Integration.Plugin.Handlers;
 using Ringtoets.Integration.Plugin.Properties;
 using Ringtoets.Integration.Service.Comparers;
 using CoreCommonGuiResources = Core.Common.Gui.Properties.Resources;
@@ -45,6 +46,7 @@
         private readonly Action<string, AssessmentSectionsOwner> getAssessmentSectionsAction;
         private readonly IAssessmentSectionMergeComparer comparer;
         private readonly IMergeDataProvider mergeDataProvider;
+        private readonly IAssessmentSectionMergeHandler mergeHandler;
 
         /// <summary>
         /// Creates a new instance of <see cref="AssessmentSectionMerger"/>,
@@ -54,9 +56,10 @@
         /// to merge.</param>
         /// <param name="comparer">The comparer to compare the assessment sections with.</param>
         /// <param name="mergeDataProvider">The provider to get the data to merge from.</param>
+        /// <param name="mergeHandler">The handler to perform the merge.</param>
         /// <exception cref="ArgumentNullException">Thrown when any parameter is <c>null</c>.</exception>
         public AssessmentSectionMerger(IInquiryHelper inquiryHandler, Action<string, AssessmentSectionsOwner> getAssessmentSectionsAction,
-                                       IAssessmentSectionMergeComparer comparer, IMergeDataProvider mergeDataProvider)
+                                       IAssessmentSectionMergeComparer comparer, IMergeDataProvider mergeDataProvider, IAssessmentSectionMergeHandler mergeHandler)
         {
             if (inquiryHandler == null)
             {
@@ -78,10 +81,16 @@
                 throw new ArgumentNullException(nameof(mergeDataProvider));
             }
 
+            if (mergeHandler == null)
+            {
+                throw new ArgumentNullException(nameof(mergeHandler));
+            }
+
             this.inquiryHandler = inquiryHandler;
             this.getAssessmentSectionsAction = getAssessmentSectionsAction;
             this.comparer = comparer;
             this.mergeDataProvider = mergeDataProvider;
+            this.mergeHandler = mergeHandler;
         }
 
         /// <summary>
Index: Ringtoets/Integration/src/Ringtoets.Integration.Plugin/Handlers/IAssessmentSectionMergeHandler.cs
===================================================================
diff -u -r61749a95649b845b5705ea40825b5f4257d38ed5 -r7fad62a843a5b8cd970b900800b851581e49476a
--- Ringtoets/Integration/src/Ringtoets.Integration.Plugin/Handlers/IAssessmentSectionMergeHandler.cs	(.../IAssessmentSectionMergeHandler.cs)	(revision 61749a95649b845b5705ea40825b5f4257d38ed5)
+++ Ringtoets/Integration/src/Ringtoets.Integration.Plugin/Handlers/IAssessmentSectionMergeHandler.cs	(.../IAssessmentSectionMergeHandler.cs)	(revision 7fad62a843a5b8cd970b900800b851581e49476a)
@@ -28,7 +28,7 @@
     /// <summary>
     /// Interface for handling the merge of the <see cref="AssessmentSection"/>.
     /// </summary>
-    internal interface IAssessmentSectionMergeHandler
+    public interface IAssessmentSectionMergeHandler
     {
         /// <summary>
         /// Performs the merges.
Index: Ringtoets/Integration/src/Ringtoets.Integration.Plugin/RingtoetsPlugin.cs
===================================================================
diff -u -r5d6ebe2e900dc53874bae15126eaa813b504da3c -r7fad62a843a5b8cd970b900800b851581e49476a
--- Ringtoets/Integration/src/Ringtoets.Integration.Plugin/RingtoetsPlugin.cs	(.../RingtoetsPlugin.cs)	(revision 5d6ebe2e900dc53874bae15126eaa813b504da3c)
+++ Ringtoets/Integration/src/Ringtoets.Integration.Plugin/RingtoetsPlugin.cs	(.../RingtoetsPlugin.cs)	(revision 7fad62a843a5b8cd970b900800b851581e49476a)
@@ -282,7 +282,8 @@
                                                                       assessmentSectionOwner.AssessmentSections = provider.GetAssessmentSections(filePath);
                                                                   },
                                                                   new AssessmentSectionMergeComparer(),
-                                                                  new MergeDataProviderStub(Gui.MainWindow));
+                                                                  new MergeDataProviderStub(Gui.MainWindow),
+                                                                  new AssessmentSectionMergeHandlerStub());
 
             ribbonCommandHandler = new RingtoetsRibbon
             {
Index: Ringtoets/Integration/test/Ringtoets.Integration.Plugin.Test/AssessmentSectionMergerTest.cs
===================================================================
diff -u -r36fb70b04307e0805488e2862cd94b1820f6bb1e -r7fad62a843a5b8cd970b900800b851581e49476a
--- Ringtoets/Integration/test/Ringtoets.Integration.Plugin.Test/AssessmentSectionMergerTest.cs	(.../AssessmentSectionMergerTest.cs)	(revision 36fb70b04307e0805488e2862cd94b1820f6bb1e)
+++ Ringtoets/Integration/test/Ringtoets.Integration.Plugin.Test/AssessmentSectionMergerTest.cs	(.../AssessmentSectionMergerTest.cs)	(revision 7fad62a843a5b8cd970b900800b851581e49476a)
@@ -29,6 +29,7 @@
 using Ringtoets.Integration.Data;
 using Ringtoets.Integration.Data.Merge;
 using Ringtoets.Integration.Forms.Merge;
+using Ringtoets.Integration.Plugin.Handlers;
 using Ringtoets.Integration.Service.Comparers;
 
 namespace Ringtoets.Integration.Plugin.Test
@@ -43,10 +44,11 @@
             var mocks = new MockRepository();
             var comparer = mocks.StrictMock<IAssessmentSectionMergeComparer>();
             var mergeDataProvider = mocks.StrictMock<IMergeDataProvider>();
+            var mergeHandler = mocks.StrictMock<IAssessmentSectionMergeHandler>();
             mocks.ReplayAll();
 
             // Call
-            TestDelegate call = () => new AssessmentSectionMerger(null, (path, owner) => {}, comparer, mergeDataProvider);
+            TestDelegate call = () => new AssessmentSectionMerger(null, (path, owner) => {}, comparer, mergeDataProvider, mergeHandler);
 
             // Assert
             var exception = Assert.Throws<ArgumentNullException>(call);
@@ -62,10 +64,11 @@
             var inquiryHelper = mocks.StrictMock<IInquiryHelper>();
             var comparer = mocks.StrictMock<IAssessmentSectionMergeComparer>();
             var mergeDataProvider = mocks.StrictMock<IMergeDataProvider>();
+            var mergeHandler = mocks.StrictMock<IAssessmentSectionMergeHandler>();
             mocks.ReplayAll();
 
             // Call
-            TestDelegate call = () => new AssessmentSectionMerger(inquiryHelper, null, comparer, mergeDataProvider);
+            TestDelegate call = () => new AssessmentSectionMerger(inquiryHelper, null, comparer, mergeDataProvider, mergeHandler);
 
             // Assert
             var exception = Assert.Throws<ArgumentNullException>(call);
@@ -80,10 +83,11 @@
             var mocks = new MockRepository();
             var inquiryHelper = mocks.StrictMock<IInquiryHelper>();
             var mergeDataProvider = mocks.StrictMock<IMergeDataProvider>();
+            var mergeHandler = mocks.StrictMock<IAssessmentSectionMergeHandler>();
             mocks.ReplayAll();
 
             // Call
-            TestDelegate call = () => new AssessmentSectionMerger(inquiryHelper, (path, owner) => {}, null, mergeDataProvider);
+            TestDelegate call = () => new AssessmentSectionMerger(inquiryHelper, (path, owner) => {}, null, mergeDataProvider, mergeHandler);
 
             // Assert
             var exception = Assert.Throws<ArgumentNullException>(call);
@@ -98,10 +102,11 @@
             var mocks = new MockRepository();
             var inquiryHelper = mocks.StrictMock<IInquiryHelper>();
             var comparer = mocks.StrictMock<IAssessmentSectionMergeComparer>();
+            var mergeHandler = mocks.StrictMock<IAssessmentSectionMergeHandler>();
             mocks.ReplayAll();
 
             // Call
-            TestDelegate call = () => new AssessmentSectionMerger(inquiryHelper, (path, owner) => {}, comparer, null);
+            TestDelegate call = () => new AssessmentSectionMerger(inquiryHelper, (path, owner) => {}, comparer, null, mergeHandler);
 
             // Assert
             var exception = Assert.Throws<ArgumentNullException>(call);
@@ -110,16 +115,36 @@
         }
 
         [Test]
+        public void Constructor_MergeHandlerNull_ThrowsArgumentNullException()
+        {
+            // Setup
+            var mocks = new MockRepository();
+            var inquiryHelper = mocks.StrictMock<IInquiryHelper>();
+            var comparer = mocks.StrictMock<IAssessmentSectionMergeComparer>();
+            var mergeDataProvider = mocks.StrictMock<IMergeDataProvider>();
+            mocks.ReplayAll();
+
+            // Call
+            TestDelegate call = () => new AssessmentSectionMerger(inquiryHelper, (path, owner) => {}, comparer, mergeDataProvider, null);
+
+            // Assert
+            var exception = Assert.Throws<ArgumentNullException>(call);
+            Assert.AreEqual("mergeHandler", exception.ParamName);
+            mocks.VerifyAll();
+        }
+
+        [Test]
         public void StartMerge_AssessmentSectionNull_ThrowsArgumentNullException()
         {
             // Setup
             var mocks = new MockRepository();
             var inquiryHelper = mocks.StrictMock<IInquiryHelper>();
             var comparer = mocks.StrictMock<IAssessmentSectionMergeComparer>();
             var mergeDataProvider = mocks.StrictMock<IMergeDataProvider>();
+            var mergeHandler = mocks.StrictMock<IAssessmentSectionMergeHandler>();
             mocks.ReplayAll();
 
-            var merger = new AssessmentSectionMerger(inquiryHelper, (path, owner) => {}, comparer, mergeDataProvider);
+            var merger = new AssessmentSectionMerger(inquiryHelper, (path, owner) => {}, comparer, mergeDataProvider, mergeHandler);
 
             // Call
             TestDelegate call = () => merger.StartMerge(null);
@@ -139,9 +164,10 @@
             inquiryHelper.Expect(helper => helper.GetSourceFileLocation(null)).IgnoreArguments().Return(null);
             var comparer = mocks.StrictMock<IAssessmentSectionMergeComparer>();
             var mergeDataProvider = mocks.StrictMock<IMergeDataProvider>();
+            var mergeHandler = mocks.StrictMock<IAssessmentSectionMergeHandler>();
             mocks.ReplayAll();
 
-            var merger = new AssessmentSectionMerger(inquiryHelper, (path, owner) => {}, comparer, mergeDataProvider);
+            var merger = new AssessmentSectionMerger(inquiryHelper, (path, owner) => {}, comparer, mergeDataProvider, mergeHandler);
 
             // Call
             Action call = () => merger.StartMerge(new AssessmentSection(AssessmentSectionComposition.Dike));
@@ -160,9 +186,10 @@
             inquiryHelper.Expect(helper => helper.GetSourceFileLocation(null)).IgnoreArguments().Return(string.Empty);
             var comparer = mocks.StrictMock<IAssessmentSectionMergeComparer>();
             var mergeDataProvider = mocks.StrictMock<IMergeDataProvider>();
+            var mergeHandler = mocks.StrictMock<IAssessmentSectionMergeHandler>();
             mocks.ReplayAll();
 
-            var merger = new AssessmentSectionMerger(inquiryHelper, (path, owner) => {}, comparer, mergeDataProvider);
+            var merger = new AssessmentSectionMerger(inquiryHelper, (path, owner) => {}, comparer, mergeDataProvider, mergeHandler);
 
             // When
             Action call = () => merger.StartMerge(new AssessmentSection(AssessmentSectionComposition.Dike));
@@ -181,14 +208,12 @@
             inquiryHelper.Expect(helper => helper.GetSourceFileLocation(null)).IgnoreArguments().Return(string.Empty);
             var comparer = mocks.StrictMock<IAssessmentSectionMergeComparer>();
             var mergeDataProvider = mocks.StrictMock<IMergeDataProvider>();
+            var mergeHandler = mocks.StrictMock<IAssessmentSectionMergeHandler>();
             mocks.ReplayAll();
 
-            Action<string, AssessmentSectionsOwner> getAssessmentSectionsAction = (path, owner) =>
-            {
-                owner.AssessmentSections = Enumerable.Empty<AssessmentSection>();
-            };
+            Action<string, AssessmentSectionsOwner> getAssessmentSectionsAction = (path, owner) => { owner.AssessmentSections = Enumerable.Empty<AssessmentSection>(); };
 
-            var merger = new AssessmentSectionMerger(inquiryHelper, getAssessmentSectionsAction, comparer, mergeDataProvider);
+            var merger = new AssessmentSectionMerger(inquiryHelper, getAssessmentSectionsAction, comparer, mergeDataProvider, mergeHandler);
 
             // When
             Action call = () => merger.StartMerge(new AssessmentSection(AssessmentSectionComposition.Dike));
@@ -208,17 +233,18 @@
             var comparer = mocks.StrictMock<IAssessmentSectionMergeComparer>();
             comparer.Expect(c => c.Compare(null, null)).IgnoreArguments().Return(false);
             var mergeDataProvider = mocks.StrictMock<IMergeDataProvider>();
+            var mergeHandler = mocks.StrictMock<IAssessmentSectionMergeHandler>();
             mocks.ReplayAll();
 
             Action<string, AssessmentSectionsOwner> getAssessmentSectionsAction = (path, owner) =>
             {
-                owner.AssessmentSections = new []
+                owner.AssessmentSections = new[]
                 {
                     new AssessmentSection(AssessmentSectionComposition.Dike)
                 };
             };
 
-            var merger = new AssessmentSectionMerger(inquiryHelper, getAssessmentSectionsAction, comparer, mergeDataProvider);
+            var merger = new AssessmentSectionMerger(inquiryHelper, getAssessmentSectionsAction, comparer, mergeDataProvider, mergeHandler);
 
             // When
             Action call = () => merger.StartMerge(new AssessmentSection(AssessmentSectionComposition.Dike));
@@ -239,17 +265,18 @@
             comparer.Expect(c => c.Compare(null, null)).IgnoreArguments().Return(true);
             var mergeDataProvider = mocks.StrictMock<IMergeDataProvider>();
             mergeDataProvider.Expect(mdp => mdp.SelectData(null)).IgnoreArguments().Return(false);
+            var mergeHandler = mocks.StrictMock<IAssessmentSectionMergeHandler>();
             mocks.ReplayAll();
 
             Action<string, AssessmentSectionsOwner> getAssessmentSectionsAction = (path, owner) =>
             {
-                owner.AssessmentSections = new []
+                owner.AssessmentSections = new[]
                 {
                     new AssessmentSection(AssessmentSectionComposition.Dike)
                 };
             };
 
-            var merger = new AssessmentSectionMerger(inquiryHelper, getAssessmentSectionsAction, comparer, mergeDataProvider);
+            var merger = new AssessmentSectionMerger(inquiryHelper, getAssessmentSectionsAction, comparer, mergeDataProvider, mergeHandler);
 
             // When
             Action call = () => merger.StartMerge(new AssessmentSection(AssessmentSectionComposition.Dike));
@@ -271,17 +298,18 @@
             var mergeDataProvider = mocks.StrictMock<IMergeDataProvider>();
             mergeDataProvider.Expect(mdp => mdp.SelectData(null)).IgnoreArguments().Return(true);
             mergeDataProvider.Expect(mdp => mdp.SelectedAssessmentSection).Return(null);
+            var mergeHandler = mocks.StrictMock<IAssessmentSectionMergeHandler>();
             mocks.ReplayAll();
 
             Action<string, AssessmentSectionsOwner> getAssessmentSectionsAction = (path, owner) =>
             {
-                owner.AssessmentSections = new []
+                owner.AssessmentSections = new[]
                 {
                     new AssessmentSection(AssessmentSectionComposition.Dike)
                 };
             };
 
-            var merger = new AssessmentSectionMerger(inquiryHelper, getAssessmentSectionsAction, comparer, mergeDataProvider);
+            var merger = new AssessmentSectionMerger(inquiryHelper, getAssessmentSectionsAction, comparer, mergeDataProvider, mergeHandler);
 
             // When
             Action call = () => merger.StartMerge(new AssessmentSection(AssessmentSectionComposition.Dike));
@@ -304,17 +332,18 @@
             mergeDataProvider.Expect(mdp => mdp.SelectData(null)).IgnoreArguments().Return(true);
             mergeDataProvider.Expect(mdp => mdp.SelectedAssessmentSection).Return(new AssessmentSection(AssessmentSectionComposition.Dike));
             mergeDataProvider.Expect(mdp => mdp.SelectedFailureMechanisms).Return(null);
+            var mergeHandler = mocks.StrictMock<IAssessmentSectionMergeHandler>();
             mocks.ReplayAll();
 
             Action<string, AssessmentSectionsOwner> getAssessmentSectionsAction = (path, owner) =>
             {
-                owner.AssessmentSections = new []
+                owner.AssessmentSections = new[]
                 {
                     new AssessmentSection(AssessmentSectionComposition.Dike)
                 };
             };
 
-            var merger = new AssessmentSectionMerger(inquiryHelper, getAssessmentSectionsAction, comparer, mergeDataProvider);
+            var merger = new AssessmentSectionMerger(inquiryHelper, getAssessmentSectionsAction, comparer, mergeDataProvider, mergeHandler);
 
             // When
             Action call = () => merger.StartMerge(new AssessmentSection(AssessmentSectionComposition.Dike));