diff --git a/modules/sale_supply/purchase.py b/modules/sale_supply/purchase.py
index 4ed25eb64f..23a123a7ff 100644
--- a/modules/sale_supply/purchase.py
+++ b/modules/sale_supply/purchase.py
@@ -18,6 +18,12 @@ class Request(metaclass=PoolMeta):
     def _get_origin(cls):
         return super()._get_origin() | {'sale.sale'}
 
+    @classmethod
+    def copy(cls, requests, default=None):
+        default = default.copy() if default is not None else {}
+        default.setdefault('sale_lines')
+        return super().copy(requests, default=default)
+
     @classmethod
     def delete(cls, requests):
         pool = Pool()