How can we implement drop shipment on Purchase order

Business Scenario.

In our NB type purchase order we are processing a lot of drop shipment. ( drop shipment means buying something from one vendor to shipping to another vendor, This NOT a subcontracting PO )

How

We place a PO where on  PO line item details tab we put vendor Number on Delivery address. As soon as we put vendor number, its overwrite my original delivery  address  and  its populate with vendor address.

My  question

How I can process  if vendor has different shipping address than whatever we have in our vendor master data .

Possible Solution : maintianing partner function on vendor master ( for example keeping PI as corporate address and OA as real shipping address, but I can not create new vendor number )

without creating New vendor how can I populate shipping adress on my PO delivery tab. is there any config possible on PO type

Solution will be appreciated .