Primary ledger vs. Reporting currency

We upgraded to R12.1.3 in Nov 2014 and have one legal entity, one ledger, and multiple balancing segments which represent affiliates from various parts of the world. Our functional currency is USD.  We have the balancing segment value set assigned to the legal entity but do not have specific balancing segments assigned to the legal entity or ledger.  We now have requirement to report one or more of the balancing segments in a foreign currency.  Since we do not want all of the balancing segments in our primary ledger to report in that foreign currency, would it be better to setup a new primary ledger with a reporting ledger instead of using reporting currencies on the existing primary ledger?