It's not BA, but I just received their highest class for AS mileage credit (150% EQM & 250% RDM), after bidding on a POUG from Y to J from IcelandAir's 'Class Up' preflight email.
I am happy with the outcome, but when I asked AS for clarification, I received this reply yesterday from the AS agent who processed my mileage request:
"July 30, 2021
Dear Mark,
Mileage Plan miles are credited per our partnership with the airline partner using the class of service on the itinerary receipt. Although boarding passes are used to confirm travel, we cannot use the class of service information from the boarding pass directly. If there was a change in the class of service for your itinerary, please send our team a copy of your updated itinerary receipt so we can make changes..."
In contrast to AS' statement above, I still received the highest fare class miles, even though I only submitted my original Y-class itinerary receipt with my boarding pass for mileage credit.
FI never sent me any email confirmation after bidding or receiving an upgrade. So AS either went by my boarding pass (which showed the upgraded J class) or was able to see the upgrade reflected in my booking reference/ticket#.
Based on this, I would add your AS MP# into the BA reservation and hope it processes automatically (as BA did for the other upgraded FTers in the linked thread above). If that doesn't work, then you can submit for AS for mileage credit. But I would screenshot your upgrade's payment confirmation page, just in case you need a receipt for show the class of service change.
Either way, hope you're able to get WTP-level miles for your BA Y ticket!
Last edited by mixmastermark; Aug 1, 2021 at 10:47 am