Originally Posted by
sydneyracquelle
Have him book it online on either his or your Amex card and make you the primary traveler and him the companion.
This. While brother has to book from his account, he can specify someone other than himself as the primary traveller who will get the credit for the flight. No need to go through an agent. Also, you will probably want to verify there are at least two seats available in L/U/T/X/V fare classes (assuming this is for Main tickets) on flights you want first (otherwise, brother's attempt to use cert on flights will be fruitless).