diff --git a/app/Models/Expense.php b/app/Models/Expense.php
index c36a8f67cb..e79c0fb4c0 100644
--- a/app/Models/Expense.php
+++ b/app/Models/Expense.php
@@ -105,7 +105,7 @@ class Expense extends BaseModel
 
     public function purchase_order()
     {
-        return $this->belongsTo(PurchaseOrder::class);
+        return $this->hasOne(PurchaseOrder::class);
     }
 
     public function translate_entity()
diff --git a/app/Models/PurchaseOrder.php b/app/Models/PurchaseOrder.php
index ee25e0cc7a..d34062b513 100644
--- a/app/Models/PurchaseOrder.php
+++ b/app/Models/PurchaseOrder.php
@@ -169,7 +169,7 @@ class PurchaseOrder extends BaseModel
 
     public function expense()
     {
-        return $this->hasOne(Expense::class);
+        return $this->belongsTo(Expense::class);
     }
 
     public function user()
diff --git a/app/Transformers/ExpenseTransformer.php b/app/Transformers/ExpenseTransformer.php
index 17143e29ef..aa191ab73a 100644
--- a/app/Transformers/ExpenseTransformer.php
+++ b/app/Transformers/ExpenseTransformer.php
@@ -94,7 +94,6 @@ class ExpenseTransformer extends EntityTransformer
             'uses_inclusive_taxes' => (bool) $expense->uses_inclusive_taxes,
             'calculate_tax_by_amount' => (bool) $expense->calculate_tax_by_amount,
             'entity_type' => 'expense',
-            'purchase_order_id' => (string) $this->encodePrimaryKey($expense->purchase_order_id),
         ];
     }
 }
diff --git a/app/Transformers/PurchaseOrderTransformer.php b/app/Transformers/PurchaseOrderTransformer.php
index 5364a534c2..0e21a84148 100644
--- a/app/Transformers/PurchaseOrderTransformer.php
+++ b/app/Transformers/PurchaseOrderTransformer.php
@@ -26,6 +26,10 @@ class PurchaseOrderTransformer extends EntityTransformer
         'documents'
     ];
 
+    protected $availableIncludes = [
+        'expense'
+    ];
+
     public function includeInvitations(PurchaseOrder $purchase_order)
     {
         $transformer = new PurchaseOrderInvitationTransformer($this->serializer);
@@ -41,6 +45,13 @@ class PurchaseOrderTransformer extends EntityTransformer
         return $this->includeCollection($purchase_order->documents, $transformer, Document::class);
     }
     
+    public function includeExpense(PurchaseOrder $purchase_order)
+    {
+        $transformer = new ExpenseTransformer($this->serializer);
+
+        return $this->includeItem($purchase_order->expense, $transformer, Document::class);
+    }
+
     public function transform(PurchaseOrder $purchase_order)
     {
         return [
@@ -103,6 +114,7 @@ class PurchaseOrderTransformer extends EntityTransformer
             'exchange_rate' => (float)$purchase_order->exchange_rate,
             'paid_to_date' => (float)$purchase_order->paid_to_date,
             'subscription_id' => $this->encodePrimaryKey($purchase_order->subscription_id),
+            'expense_id' => $this->encodePrimaryKey($purchase_order->expense_id),
         ];
     }
 
diff --git a/database/migrations/2022_07_06_080127_add_purchase_order_to_expense.php b/database/migrations/2022_07_06_080127_add_purchase_order_to_expense.php
index bd7b44e514..571d77b9c8 100644
--- a/database/migrations/2022_07_06_080127_add_purchase_order_to_expense.php
+++ b/database/migrations/2022_07_06_080127_add_purchase_order_to_expense.php
@@ -25,26 +25,22 @@ class AddPurchaseOrderToExpense extends Migration
      */
     public function up()
     {
-        Schema::table('expenses', function (Blueprint $table) {
-            $table->unsignedInteger('purchase_order_id')->nullable()->index();
+        Schema::table('purchase_orders', function (Blueprint $table) {
+            $table->unsignedInteger('expense_id')->nullable()->index();
         });
 
         PurchaseOrder::withTrashed()->where('status_id', 4)->update(['status_id' => 5]);
 
 
-        $language = Language::find(33);
+        $language = Language::where('locale', 'bg')->first();
 
         if(!$language)
         {
-            Language::unguard();
 
             $l = new Language();
-            $l->id = 33;
             $l->name = "Bulgarian";
             $l->locale = "bg";
             $l->save();
-
-            Language::reguard();
             
             $this->buildCache(true);
         }
diff --git a/database/seeders/LanguageSeeder.php b/database/seeders/LanguageSeeder.php
index f871f4a572..6e2541ffbf 100644
--- a/database/seeders/LanguageSeeder.php
+++ b/database/seeders/LanguageSeeder.php
@@ -56,7 +56,6 @@ class LanguageSeeder extends Seeder
             ['id' => 30, 'name' => 'Arabic', 'locale' => 'ar'],
             ['id' => 31, 'name' => 'Persian', 'locale' => 'fa'],
             ['id' => 32, 'name' => 'Latvian', 'locale' => 'lv_LV'],
-            ['id' => 33, 'name' => 'Bulgarian', 'locale' => 'bg'],
         ];
 
         foreach ($languages as $language) {