T-code required for Substitution

Hi all,

This is regarding the query on substitution that I want to write, as per my knowledge t-code OBBH is used for FI substitutions. But when I came across the t-code GGB1 there I found the application area as sales order specific substitution where the field were all sales order specific, BUT if i want to write a substitution for Purchase order/Stock transport order.....is there any specific t-code for PO/STO similar to Sale order,as i want to create a specific Set directory in application area Profit Centre Accounting which need to be mapped as prerequsite in GGB1.

I am finding a structure PCASUB but it does not have values related to field vendor - LIFNR which is not available.

For any further information please revert..

Would appreicate the help & quick response.

Regards

S