How can I secure balance transfer drill down?

The balance transfer drill-down feature is secured with the same privilege that controls the existing account balance inquiry features.

A specific data access set is not required to drill down from the target ledger to the source ledger to view the balance transfer information. As long as you have read or write access to the target ledger you can drill down to the source ledger. However, you are limited to just that drill path and cannot see other journals for the target ledger.