It is a long shot, but:

If you call AAdvantage Customer Service (or the EXP desk) and explain the problem to them, they may be able to pre-arrange for "Original Routing Credit," as the change in carrier is involuntary, and due to an AA-schedule change.

If it works, you could take the BA flight, avoid the overnight, and get your miles.

It's free to ask... good luck.

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