diff --git a/KVA/Migration.Tool.Source/Mappers/CmsClassMapper.cs b/KVA/Migration.Tool.Source/Mappers/CmsClassMapper.cs
index 87ca1499..3692a248 100644
--- a/KVA/Migration.Tool.Source/Mappers/CmsClassMapper.cs
+++ b/KVA/Migration.Tool.Source/Mappers/CmsClassMapper.cs
@@ -1,6 +1,5 @@
 using System.Diagnostics;
 using System.Xml;
-
 using CMS.ContentEngine;
 using CMS.Core;
 using CMS.DataEngine;
@@ -55,6 +54,8 @@ protected override DataClassInfo MapInternal(ICmsClass source, DataClassInfo tar
             logger.LogDebug("{ClassName} is {@Properties}", source.ClassName, new { isCustomizableSystemClass, classIsCustom, source.ClassResourceID, classResource?.ResourceName });
         }
 
+        var existingFieldGUIDs = new FormInfo(target.ClassFormDefinition).ItemsList.OfType<FormFieldInfo>().ToDictionary(x => x.Name, x => x.Guid);
+
         FormDefinitionHelper.MapFormDefinitionFields(logger, fieldMigrationService, source, target, isCustomizableSystemClass, classIsCustom);
 
         target.ClassHasUnmanagedDbSchema = false;
@@ -141,7 +142,7 @@ protected override DataClassInfo MapInternal(ICmsClass source, DataClassInfo tar
                 target.ClassType = ClassType.OTHER;
                 target.ClassContentTypeType = null;
 
-                target = PatchDataClassInfo(target, out string? oldPrimaryKeyName, out string? documentNameField);
+                target = PatchDataClassInfo(target, existingFieldGUIDs, out string? oldPrimaryKeyName, out string? documentNameField);
 
                 break;
             }
@@ -175,7 +176,7 @@ protected override DataClassInfo MapInternal(ICmsClass source, DataClassInfo tar
                 target.ClassType = ClassType.CONTENT_TYPE;
                 target.ClassContentTypeType = ClassContentTypeType.REUSABLE;
 
-                target = PatchDataClassInfo(target, out string? oldPrimaryKeyName, out string? documentNameField);
+                target = PatchDataClassInfo(target, existingFieldGUIDs, out string? oldPrimaryKeyName, out string? documentNameField);
                 break;
             }
 
@@ -193,7 +194,7 @@ protected override DataClassInfo MapInternal(ICmsClass source, DataClassInfo tar
                     ? ClassContentTypeType.REUSABLE
                     : ClassContentTypeType.WEBSITE;
 
-                target = PatchDataClassInfo(target, out string? oldPrimaryKeyName, out string? documentNameField);
+                target = PatchDataClassInfo(target, existingFieldGUIDs, out string? oldPrimaryKeyName, out string? documentNameField);
                 break;
             }
 
@@ -204,7 +205,7 @@ protected override DataClassInfo MapInternal(ICmsClass source, DataClassInfo tar
         return target;
     }
 
-    public static DataClassInfo PatchDataClassInfo(DataClassInfo dataClass, out string? oldPrimaryKeyName, out string? documentNameField)
+    public static DataClassInfo PatchDataClassInfo(DataClassInfo dataClass, Dictionary<string, Guid> existingFieldGUIDs, out string? oldPrimaryKeyName, out string? documentNameField)
     {
         oldPrimaryKeyName = null;
         documentNameField = null;
@@ -213,13 +214,22 @@ public static DataClassInfo PatchDataClassInfo(DataClassInfo dataClass, out stri
             var fi = new FormInfo(dataClass.ClassFormDefinition);
             string tableName = dataClass.ClassTableName;
             var contentTypeManager = Service.Resolve<IContentTypeManager>();
+
             contentTypeManager.Initialize(dataClass);
+
             if (!string.IsNullOrWhiteSpace(tableName))
             {
                 dataClass.ClassTableName = tableName;
             }
 
             var nfi = new FormInfo(dataClass.ClassFormDefinition);
+            foreach (var item in nfi.ItemsList.OfType<FormFieldInfo>())
+            {
+                if (existingFieldGUIDs.TryGetValue(item.Name, out var existingGUID))
+                {
+                    item.Guid = existingGUID;
+                }
+            }
 
             foreach (var dataDefinitionItem in fi.GetFormElements(true, true) ?? [])
             {
diff --git a/KVA/Migration.Tool.Source/Providers/ClassMappingProvider.cs b/KVA/Migration.Tool.Source/Providers/ClassMappingProvider.cs
index 3630e76a..823a5963 100644
--- a/KVA/Migration.Tool.Source/Providers/ClassMappingProvider.cs
+++ b/KVA/Migration.Tool.Source/Providers/ClassMappingProvider.cs
@@ -147,7 +147,7 @@ private Dictionary<string, IClassMapping> MappingsByClassName
             if (!hasFieldsAlready)
             {
                 FormDefinitionHelper.MapFormDefinitionFields(logger, fieldMigrationService, nfi.GetXmlDefinition(), false, true, newDt, false, false);
-                CmsClassMapper.PatchDataClassInfo(newDt, out _, out _);
+                CmsClassMapper.PatchDataClassInfo(newDt, [], out _, out _);
             }
 
             if (classMapping.TargetFieldPatchers.Count > 0)
diff --git a/KVA/Migration.Tool.Source/Services/ReusableSchemaService.cs b/KVA/Migration.Tool.Source/Services/ReusableSchemaService.cs
index 5e48c95f..dff3f196 100644
--- a/KVA/Migration.Tool.Source/Services/ReusableSchemaService.cs
+++ b/KVA/Migration.Tool.Source/Services/ReusableSchemaService.cs
@@ -88,8 +88,11 @@ public void AddReusableSchemaToDataClass(DataClassInfo dataClassInfo, string reu
     {
         var formInfo = new FormInfo(dataClassInfo.ClassFormDefinition);
         var schema = reusableFieldSchemaManager.Get(reusableFieldSchemaName);
-        formInfo.AddFormItem(new FormSchemaInfo { Name = dataClassInfo.ClassName, Guid = schema.Guid });
-        dataClassInfo.ClassFormDefinition = formInfo.GetXmlDefinition();
+        if (!formInfo.ItemsList.Any(x => x is FormSchemaInfo fsi && fsi.Guid == schema.Guid))
+        {
+            formInfo.AddFormItem(new FormSchemaInfo { Name = dataClassInfo.ClassName, Guid = schema.Guid });
+            dataClassInfo.ClassFormDefinition = formInfo.GetXmlDefinition();
+        }
     }
 
     public IEnumerable<FormFieldInfo> GetFieldsFromReusableSchema(DataClassInfo dataClassInfo)