Excuse me if this is already answered, dug around quite a bit.

I recently booked LHR-JFK on BA.com, flying on the 77W.

AA offered a Y-J upgrade at airport for 270GBP.
I took the upgrade.

Usually on BA airport upgrades I would receive the additional mileage for the cabin flown.

I credited the miles to AA, which posted for Y.

If you purchase airport upgrades from AA do you earn the miles for the cabin flown?

Fantastic J product and very reasonable upgrade fee. Great job, AA!