Mode of Payment Accounts with Company and Branch

I would like to add Branch as additional column for Mode of Payment Accounts.
I have tried using the customize feature to add new field in the child table, but unable to save because “same company entered more than once”.

How can I achieve this customization?

The purpose of this customization to reduce Mode of Payment options and setup default account for each Mode of Payment based on Branch. (or maybe POS Profile).

After I check “Mode of Payment Account” doctype, its is read-only.

Any suggestion?