Echo. I'm assuming that your corporate Amex is close enough to ours... but the Amex folks should know how to book an itinerary with some given $$$ on the corporate account, and then the buy-up on your personal card. When I've done this, our corporate discount has still been applied, Amex is just taking two separate cards as payment. I think they charge a nominal processing fee for this, but if you're buying up to C that amount is a rounding error. ;-)