We have an existing custom field showing Total available quantity from the same site the requisition exists: INVENTORY_PART_IN_STOCK_API.Get_Avail_Plan_Qty_Loc_Type(CONTRACT,PART_NO,NULL,NULL,'AVAILABLE',NULL,'PICKING','F','SHIPMENT','MANUFACTURING')

but now I should need to modify this  expression to show it from the warehouse site. How can I do that?