diff --git a/.DS_Store b/.DS_Store
index 359e843..c37d51b 100644
Binary files a/.DS_Store and b/.DS_Store differ
diff --git a/app/.DS_Store b/app/.DS_Store
index 32630bc..6d4445f 100644
Binary files a/app/.DS_Store and b/app/.DS_Store differ
diff --git a/app/Enums/.DS_Store b/app/Enums/.DS_Store
index 4b5683b..38c792f 100644
Binary files a/app/Enums/.DS_Store and b/app/Enums/.DS_Store differ
diff --git a/app/Http/Controllers/Api/Admin/Order/OrderController.php b/app/Http/Controllers/Api/Admin/Order/OrderController.php
index d6259ca..a9ddc12 100644
--- a/app/Http/Controllers/Api/Admin/Order/OrderController.php
+++ b/app/Http/Controllers/Api/Admin/Order/OrderController.php
@@ -88,7 +88,7 @@ class OrderController extends Controller
 
     public function destroy(int $id): JsonResponse
     {
-        $order = Order::with('invoice', 'invoice.invoiceItem')->find($id);
+        $order = Order::with('invoice', 'invoice.invoiceItems')->find($id);
 
         abort_if(!$order, 404, "Can't find order by ID #{$id}");
 
diff --git a/app/Http/Controllers/admin/OrderController.php b/app/Http/Controllers/admin/OrderController.php
index 79ec47c..718ada9 100644
--- a/app/Http/Controllers/admin/OrderController.php
+++ b/app/Http/Controllers/admin/OrderController.php
@@ -270,7 +270,7 @@ class OrderController extends Controller
 
     public function edit(int $id = 0)
     {
-        $order = $this->orderRepository->findWithRelationships($id, ['orderItem', 'user', 'customer.invoiceItem.type', 'payment', 'discount', 'invoice.invoiceItem']);
+        $order = $this->orderRepository->findWithRelationships($id, ['orderItem', 'user', 'customer.invoiceItem.type', 'payment', 'discount', 'invoice.invoiceItems']);
 
         if (!$order) {
             return redirect()->route('administrator.pages.order.index')->withErrors('Can\'t find a order by order id #' . $id);
diff --git a/app/Jobs/.DS_Store b/app/Jobs/.DS_Store
index 6c6d725..b6f6453 100644
Binary files a/app/Jobs/.DS_Store and b/app/Jobs/.DS_Store differ
diff --git a/app/Repositories/.DS_Store b/app/Repositories/.DS_Store
index 32e84d3..c38ed63 100644
Binary files a/app/Repositories/.DS_Store and b/app/Repositories/.DS_Store differ
diff --git a/app/Services/.DS_Store b/app/Services/.DS_Store
index 831d459..b752355 100644
Binary files a/app/Services/.DS_Store and b/app/Services/.DS_Store differ
diff --git a/app/Services/OrderService.php b/app/Services/OrderService.php
index 4910eb3..614d680 100644
--- a/app/Services/OrderService.php
+++ b/app/Services/OrderService.php
@@ -68,7 +68,7 @@ class OrderService
     {
         DB::transaction(function () use ($order) {
             if ($order->invoice) {
-                $order->invoice->invoiceItem()->delete();
+                $order->invoice->invoiceItems()->delete();
                 $order->invoice->delete();
             }
 
diff --git a/app/Support/.DS_Store b/app/Support/.DS_Store
index e698cb6..46d2d4f 100644
Binary files a/app/Support/.DS_Store and b/app/Support/.DS_Store differ
diff --git a/database/.DS_Store b/database/.DS_Store
index fe22461..afaf4ef 100644
Binary files a/database/.DS_Store and b/database/.DS_Store differ
diff --git a/database/migrations/2024_01_31_145201_customer.php b/database/migrations/2024_01_31_145201_customer.php
index 5f44f7a..4221ef0 100644
--- a/database/migrations/2024_01_31_145201_customer.php
+++ b/database/migrations/2024_01_31_145201_customer.php
@@ -33,6 +33,7 @@ return new class extends Migration {
             $table->tinyInteger('receive_deposit')->default(1);
             $table->string('password')->nullable();
             $table->integer('credit')->default(0);
+            $table->integer('unpaid_total')->default(0);
             $table->integer('total')->default(0);
             $table->string('identity_number')->nullable();
             $table->string('front_identity_number')->nullable();
@@ -44,15 +45,9 @@ return new class extends Migration {
             $table->timestamps();
             $table->softDeletes();
 
-            $table->foreign('province_code')
-                ->references('code')
-                ->on('provinces')
-                ->onDelete('set null');
+            $table->foreign('province_code')->references('code')->on('provinces')->onDelete('set null');
 
-            $table->foreign('ward_code')
-                ->references('code')
-                ->on('wards')
-                ->onDelete('set null');
+            $table->foreign('ward_code')->references('code')->on('wards')->onDelete('set null');
 
             $table->index('province_code', 'idx_users_province');
             $table->index('ward_code', 'idx_users_ward');
diff --git a/database/migrations/2026_08_28_000000_add_legacy_id_to_order_invoice_tables.php b/database/migrations/2026_08_28_000000_add_legacy_id_to_order_invoice_tables.php
new file mode 100644
index 0000000..c3c7e1a
--- /dev/null
+++ b/database/migrations/2026_08_28_000000_add_legacy_id_to_order_invoice_tables.php
@@ -0,0 +1,34 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration {
+    public function up(): void
+    {
+        Schema::table('orders', function (Blueprint $table) {
+            $table->unsignedBigInteger('legacy_id')->nullable()->unique()->after('id');
+        });
+
+        Schema::table('invoices', function (Blueprint $table) {
+            $table->unsignedBigInteger('legacy_id')->nullable()->unique()->after('id');
+        });
+
+        Schema::table('order_items', function (Blueprint $table) {
+            $table->unsignedBigInteger('legacy_id')->nullable()->unique()->after('id');
+        });
+
+        Schema::table('invoice_items', function (Blueprint $table) {
+            $table->unsignedBigInteger('legacy_id')->nullable()->unique()->after('id');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('orders', fn (Blueprint $t) => $t->dropColumn('legacy_id'));
+        Schema::table('invoices', fn (Blueprint $t) => $t->dropColumn('legacy_id'));
+        Schema::table('order_items', fn (Blueprint $t) => $t->dropColumn('legacy_id'));
+        Schema::table('invoice_items', fn (Blueprint $t) => $t->dropColumn('legacy_id'));
+    }
+};
diff --git a/database/migrations/2026_08_28_000001_drop_unique_customers_phone.php b/database/migrations/2026_08_28_000001_drop_unique_customers_phone.php
new file mode 100644
index 0000000..f4fb8e6
--- /dev/null
+++ b/database/migrations/2026_08_28_000001_drop_unique_customers_phone.php
@@ -0,0 +1,26 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+// Multiple legitimate customers can share one phone (agency/accountant managing
+// several company accounts on one contact number) — WHMCS data confirmed this
+// isn't dirty data, so uniqueness here was the wrong constraint.
+return new class extends Migration {
+    public function up(): void
+    {
+        Schema::table('customers', function (Blueprint $table) {
+            $table->dropUnique('customers_phone_unique');
+            $table->index('phone');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('customers', function (Blueprint $table) {
+            $table->dropIndex(['phone']);
+            $table->unique('phone');
+        });
+    }
+};
diff --git a/database/migrations/2026_08_28_113713_update_column_customers_table.php b/database/migrations/2026_08_28_113713_update_column_customers_table.php
new file mode 100644
index 0000000..ca8843f
--- /dev/null
+++ b/database/migrations/2026_08_28_113713_update_column_customers_table.php
@@ -0,0 +1,28 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration {
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::table('customers', function (Blueprint $table) {
+            //
+            $table->integer('unpaid_total')->default(0)->comment('Số nợ còn thiếu')->after('total');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('customers', function (Blueprint $table) {
+            //
+        });
+    }
+};
diff --git a/public/.DS_Store b/public/.DS_Store
index e55bddd..bd21257 100644
Binary files a/public/.DS_Store and b/public/.DS_Store differ
diff --git a/public/fonts/.DS_Store b/public/fonts/.DS_Store
index 0f65c47..64959c6 100644
Binary files a/public/fonts/.DS_Store and b/public/fonts/.DS_Store differ
diff --git a/resources/.DS_Store b/resources/.DS_Store
index a1e376c..1447542 100644
Binary files a/resources/.DS_Store and b/resources/.DS_Store differ
diff --git a/storage/.DS_Store b/storage/.DS_Store
index bb9a9d2..b698e70 100644
Binary files a/storage/.DS_Store and b/storage/.DS_Store differ
diff --git a/tests/.DS_Store b/tests/.DS_Store
index 572cc6b..9f794e9 100644
Binary files a/tests/.DS_Store and b/tests/.DS_Store differ