I just booked with AA a trip that involves my return from Los Angeles on BA. It's got a BA flight number and, of course, it's BA-operated. All the flights have my BAEC number attached.

My understanding was that itineraries with BA in them appeared under Manage My Booking on the on the slick BA website, or could be added to the list.

Clearly I was wrong.

But as AA's website has no access to seat plans (and suggests I use BA.com), how do I get to play around with my seat selection? Indeed, how do I make a seat selection?

Cheers, Ian