Add Accounts to Drill Down Accounts in Reports Manager

Dear experts,

We are currently working with Oracle R12.1 apps, and we are using Reports Manager to run a custom report. This report provides account balances information and integrates them into a summarized final layout.

We run the Generic FSG Drill Template with a defined period, afterwards we click on any Group of Accounts in the left so Drill Acount Balances Window pop-up:

We need to add accounts to the Drill balance:

How can we achieve this task to fulfill our requirement?

Thanks in advance