The "F" (formerly EG) BF reward bucket must come out of a Plat account - the system will not let anything other than a Plat Onepass # redeem miles for that bucket.

The standard BF "E" reward bucket applies to all accounts. Look in co.com and try booking on your Plat account versus your wife's account and you will see different availability. Once you select the return you will see the fare code (in BOLD). If it shows as E you are OK, if it shows as F - only the Plat account can book - that is either online or on the phone.

When looking for a BF reward first try only with the long haul segment to check availability. I have seen for example a flight from EWR-GIG (which connects in GRU) as BF when only the GRU-GIG (300 miles) segment is available.