Wrong Warehouse

I am enter an order from custom from and add line 1 for item 'A' for the ship from warehouse 'ABC. After that'I am using a custom program to call process order api and using this api I created order in oracle. This order line 1 for item "A" was created for ship from warehouse "ABC". Now since we do not have any inventory in the warehouse "ABC" so it goes to backorder. So user cancels the the order line 1 from the custom order form and enters a line 2 for the item "A" using the ship from warehouse "XYZ".