Index: Ringtoets/Integration/src/Ringtoets.Integration.Forms/Merge/AssessmentSectionMergeDataProviderDialog.Designer.cs
===================================================================
diff -u -r1a5caec983007983dfc4a1b7d8b12d30c8cdc1ea -r60ac24f24bd12579564f312eb215a6dd0d193ed5
--- Ringtoets/Integration/src/Ringtoets.Integration.Forms/Merge/AssessmentSectionMergeDataProviderDialog.Designer.cs	(.../AssessmentSectionMergeDataProviderDialog.Designer.cs)	(revision 1a5caec983007983dfc4a1b7d8b12d30c8cdc1ea)
+++ Ringtoets/Integration/src/Ringtoets.Integration.Forms/Merge/AssessmentSectionMergeDataProviderDialog.Designer.cs	(.../AssessmentSectionMergeDataProviderDialog.Designer.cs)	(revision 60ac24f24bd12579564f312eb215a6dd0d193ed5)
@@ -102,7 +102,6 @@
             resources.ApplyResources(this.assessmentSectionComboBox, "assessmentSectionComboBox");
             this.assessmentSectionComboBox.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList;
             this.assessmentSectionComboBox.Name = "assessmentSectionComboBox";
-            this.assessmentSectionComboBox.SelectedIndexChanged += new System.EventHandler(this.AssessmentSectionComboBox_OnSelectedIndexChanged);
             // 
             // tableLayoutPanelForLabel
             // 
Index: Ringtoets/Integration/src/Ringtoets.Integration.Forms/Merge/AssessmentSectionMergeDataProviderDialog.cs
===================================================================
diff -u -re5dda4058c572ba943002d130b8591a90ee19ce9 -r60ac24f24bd12579564f312eb215a6dd0d193ed5
--- Ringtoets/Integration/src/Ringtoets.Integration.Forms/Merge/AssessmentSectionMergeDataProviderDialog.cs	(.../AssessmentSectionMergeDataProviderDialog.cs)	(revision e5dda4058c572ba943002d130b8591a90ee19ce9)
+++ Ringtoets/Integration/src/Ringtoets.Integration.Forms/Merge/AssessmentSectionMergeDataProviderDialog.cs	(.../AssessmentSectionMergeDataProviderDialog.cs)	(revision 60ac24f24bd12579564f312eb215a6dd0d193ed5)
@@ -78,7 +78,7 @@
                 throw new ArgumentException($@"{nameof(assessmentSections)} must at least have one element.", nameof(assessmentSections));
             }
 
-            assessmentSectionComboBox.DataSource = assessmentSections.ToArray();
+            SetComboBoxData(assessmentSections);
 
             if (ShowDialog() == DialogResult.OK)
             {
@@ -119,6 +119,7 @@
         private void InitializeComboBox()
         {
             assessmentSectionComboBox.DisplayMember = nameof(AssessmentSection.Name);
+            assessmentSectionComboBox.SelectedIndexChanged += AssessmentSectionComboBoxOnSelectedIndexChanged;
         }
 
         private void InitializeDataGridView()
@@ -153,7 +154,7 @@
 
         #region Event Handling
 
-        private void AssessmentSectionComboBox_OnSelectedIndexChanged(object sender, EventArgs eventArgs)
+        private void AssessmentSectionComboBoxOnSelectedIndexChanged(object sender, EventArgs eventArgs)
         {
             if (assessmentSectionComboBox.SelectedIndex == -1)
             {
@@ -167,6 +168,12 @@
 
         #region Data Setters
 
+        private void SetComboBoxData(IEnumerable<AssessmentSection> assessmentSections)
+        {
+            assessmentSectionComboBox.DataSource = null;
+            assessmentSectionComboBox.DataSource = assessmentSections.ToArray();
+        }
+
         private void SetDataGridViewData(AssessmentSection assessmentSection)
         {
             failureMechanismMergeDataRows = new[]