[IMP] returns: use same carrier as the original picking by default

delivery_postlogistics/__init__.py

@@ -1,2 +1,3 @@
 from . import models
 from . import postlogistics
+from . import wizard

delivery_postlogistics/wizard/__init__.py

@@ -0,0 +1 @@
+from . import stock_picking_return

delivery_postlogistics/wizard/stock_picking_return.py

@@ -0,0 +1,12 @@
+from odoo import models
+
+
+class ReturnPicking(models.TransientModel):
+    _inherit = "stock.return.picking"
+
+    def _create_returns(self):
+        new_picking, pick_type_id = super(ReturnPicking, self)._create_returns()
+        if self.picking_id.delivery_type == "postlogistics":
+            picking = self.env["stock.picking"].browse(new_picking)
+            picking.write({"carrier_id": self.picking_id.carrier_id.id})
+        return new_picking, pick_type_id