Dear Cello,
we can look at the scenario in two different ways.
1. Creating a group curreny as USD, by doing this company code can have different operating currency, but the report at the company level can be fetched with USD.
2. Creating a controlling area with USD currency and assign both company code to the same controlling area.
Kindly revert back if you have any concern on the same.
Regards,
M S Lokesh