Hello everyone. A quick update. American made changes to the itinerary as requested, though the changes weren't confirmed immediately. Rather than reticket at the time of the call, the yet-to-be ticketed reservation was placed in a queue. As it was explained to me, since my ticket was in September, the airline had time. How much time? Up to six weeks.

I received a confirmation about two weeks later, along with a refund to my Amex. The only issue is that BA and Iberia had released the space on both LHR-MAD and MAD-LHR flight segments because too much time had passed, according to a BA reservations agent. I tried explaining what had happened to an American Airlines agent who insisted that everything from their end looked fine. I politely got off the phone and made repeated calls (three in total) until an agent connected me with an agent at AA's Oneworld department who contacted BA and sorted out everything on my behalf. She was excellent.

Just sharing in case this happens to another flyer.

FWIW, the 772 from Boston to London doesn't have a first class. The 772 from London to Madrid does, though I'm still seated in business class.