As I discovered you actually have to get AE to change your name in order for your AC.com name to change - so the two do actually change together. Not that it did me any good.

What was the real challenge was getting AC IT to change my name on existing flight passes that I had already purchased - took many hours on the phone with AC IT (who actually tried really hard to be helpful). They were finally able to make the change for me, but yet again it didn't make a difference and I still get the dreaded DHP flag on bookings.