Menu/Functions for enabling AP invoice entry and full access to India tax forms

Hello,

We have a requirement to create a custom responsibility that allows invoice entry only for AP invoices in India. More specifically, we need the following access:

-  AP invoice entry

-  Full access to the "India Tax Details" and "TDS Details" forms on AP transactions, with update capability

-  Ability to Validate the AP invoice, and generate credit memo to the supplier and standard invoice to the TDS tax authority

-  Disable all other menus/functions

I have been trying to modify the menu "AP_NAVIGATE_GUI12 - India" so that the custom responsibility would meet the requirements above, but am having difficulty finding exact menus and/or functions that meet all the criteria.