Exchange Gain or Loss

Hello All,
We have one primary ledger (Currency BRL) and a secondary ledger (Currency USD).

For a Payment event, today when create payment, the create accounting
on the BRL ledger id does:

Liability: Debit

Cash: Credit

USD Leger:

Liability: Debit

Cash: Credit

Exchange Gain or Loss: Credit or Debit (depends the Exchange Rate Variation

We want to use the funcionality: Bills Payable.

so for payment event: it will account the Payment in the Future Date Payment, instead of cash.

and we do not want to account the Exchange Gain or Loss at this point, we want to do it when we Credit Cash, which means: