diff --git a/backend/src/utils/tenantMergeService.ts b/backend/src/utils/tenantMergeService.ts
index 695fc91..a0b091c 100644
--- a/backend/src/utils/tenantMergeService.ts
+++ b/backend/src/utils/tenantMergeService.ts
@@ -80,6 +80,42 @@ const remapSourceTenant = (exportData: TenantFullExport, targetTenantId: number)
     return tables
 }
 
+const splitSourceTablesByAvailability = (
+    sourceTables: Record<string, Record<string, any>[]>,
+    metadata: Record<string, MergeDatabaseMetadata>
+) => {
+    const available: Record<string, Record<string, any>[]> = {}
+    const unavailable = Object.keys(sourceTables).filter((table) => {
+        if (metadata[table]) {
+            available[table] = sourceTables[table]
+            return false
+        }
+        return sourceTables[table].length > 0
+    })
+
+    return { available, unavailable }
+}
+
+const appendUnavailableTableConflicts = (plan: TenantMergePlan, unavailableTables: string[]) => {
+    for (const table of unavailableTables.sort()) {
+        plan.items.push({
+            id: `missing-target-table:${table}`,
+            table,
+            kind: "conflict",
+            sourceKey: "Zieltabelle fehlt",
+            targetKey: null,
+            label: `Tabelle ${table} ist im Zielsystem nicht vorhanden`,
+            defaultDecision: "target",
+            allowedDecisions: ["target"],
+            differences: ["Die erforderliche Tabelle fehlt im Zielschema und muss zuerst per Migration angelegt werden."],
+            sourceRow: {},
+            targetRow: null,
+        })
+        plan.summary.conflict += 1
+    }
+    return plan
+}
+
 const loadTargetRows = async (
     client: any,
     table: string,
@@ -124,7 +160,8 @@ export const createTenantMergeDryRunWithClient = async (
     targetTenantId: number
 ): Promise<TenantMergePlan> => {
     const metadata = await loadMergeMetadata(client)
-    const sourceTables = remapSourceTenant(exportData, targetTenantId)
+    const remappedSourceTables = remapSourceTenant(exportData, targetTenantId)
+    const { available: sourceTables, unavailable } = splitSourceTablesByAvailability(remappedSourceTables, metadata)
     const targetTables: Record<string, Record<string, any>[]> = {}
 
     for (const [table, sourceRows] of Object.entries(sourceTables)) {
@@ -133,7 +170,7 @@ export const createTenantMergeDryRunWithClient = async (
         targetTables[table] = await loadTargetRows(client, table, sourceRows, tableMetadata, targetTenantId)
     }
 
-    return buildTenantMergePlan(sourceTables, targetTables, metadata)
+    return appendUnavailableTableConflicts(buildTenantMergePlan(sourceTables, targetTables, metadata), unavailable)
 }
 
 export const createTenantMergeDryRun = async (
@@ -214,7 +251,9 @@ const topologicalTableOrder = (tables: string[], metadata: Record<string, MergeD
     const ordered: string[] = []
     while (remaining.size) {
         const ready = Array.from(remaining).filter((table) =>
-            metadata[table].foreignKeys.every((foreignKey) => !remaining.has(foreignKey.referencedTable) || foreignKey.referencedTable === table)
+            (metadata[table]?.foreignKeys || []).every((foreignKey) =>
+                !remaining.has(foreignKey.referencedTable) || foreignKey.referencedTable === table
+            )
         )
         const next = ready.length ? ready.sort() : [Array.from(remaining).sort()[0]]
         for (const table of next) {
@@ -240,7 +279,8 @@ export const executeTenantMergeWithClient = async (
     decisions: Record<string, TenantMergeDecision>
 ): Promise<TenantMergeExecutionResult> => {
     const metadata = await loadMergeMetadata(client)
-    const sourceTables = remapSourceTenant(rawExportData, targetTenantId)
+    const remappedSourceTables = remapSourceTenant(rawExportData, targetTenantId)
+    const { available: sourceTables } = splitSourceTablesByAvailability(remappedSourceTables, metadata)
     const preparedExport: TenantFullExport = prepareTenantFullExportRowsForImport({
         ...rawExportData,
         tenantId: targetTenantId,
diff --git a/frontend/pages/administration/tenant-imports/[importId].vue b/frontend/pages/administration/tenant-imports/[importId].vue
index 4ecc953..5137bc9 100644
--- a/frontend/pages/administration/tenant-imports/[importId].vue
+++ b/frontend/pages/administration/tenant-imports/[importId].vue
@@ -217,12 +217,14 @@ onMounted(async () => {
           </p>
           <div v-if="item.kind === 'conflict'" class="flex flex-wrap gap-2">
             <UButton
+              v-if="item.allowedDecisions.includes('target')"
               size="sm"
               :color="decisions[item.id] === 'target' ? 'primary' : 'neutral'"
               :variant="decisions[item.id] === 'target' ? 'solid' : 'soft'"
               @click="decisions[item.id] = 'target'"
             >Ziel behalten</UButton>
             <UButton
+              v-if="item.allowedDecisions.includes('source')"
               size="sm"
               :color="decisions[item.id] === 'source' ? 'warning' : 'neutral'"
               :variant="decisions[item.id] === 'source' ? 'solid' : 'soft'"