Adding Custom fields to standard SAP-ITS application.

Hi,

A functionality requires some custom fields to be added to the standard SAP-SRM EBP ( Manage business partners) application.

If I copy the whole BBP_VENDOR_CREATE program into a Z-program, and the BBPMAININT internet service to a Z-application, then would it be feasible??

Which is the best way to add custom fields in a SAP standard ITS application.

Regards,

Goutam