Oracle Credit Management for multiple functional currencies

We are using Oracle credit management. Currently we have only one ledger with a single functional currency. There is a new requirement to implement a new ledger with a different functional currency. How will it impact oracle credit management if we want to report on the new functional currency as well?

We are using credit usage rule with multiple currencies (say rule X has USD, GBP, EUR, INR) and current functional currency is INR. Now if we want to have a new functional currency of GBP, and if I try to assign a new usage rule to the same credit profile class it says currency USD already exists. I might be doing it incorrectly. My objective is that OCM should be able to run with the new functional currency as well. What do I need to do?