Wirelessly posted (BlackBerry: BlackBerry8530/5.0.0.1030 Profile/MIDP-2.1 Configuration/CLDC-1.1 VendorID/417)

"Will BA waive it as one flight if I call them?"

It's not one flight, it's two. If you mean, will BAEC waive the telephone booking fee, probably not. But there's no reason why you can't just book it as two separate redemptions on ba.com. AA will protect you in the event of IRROPS, and if you need to cancel, it will cost you just $5 USD to have your Avios restored, regardless of whether you book it as one redemption or two.

If you do book at ba.com, book the flight that has the least number of available reward seats first.