Options are:
We can implemet EXITs(screen and function exit) or BADIS.
The exit for the purpose have already been implemented so this option is no more available. For BADIs we need to implement two BADIS ME_GUI_PO_CUST and ME_PROCESS_PO_CUST. Both the badis are not of mutiple use type (as shown in screen below) and so we can have only one active implementation ACTIVE at a time I find that the second Badi ie me_process_po_cust is already implemented by SAP with implementation name as CON_FIN_SUBCONTRACT.
In such a scenario please advise a simple and easy solution........