Unfortunately, that (See ffay005) seems to be the case. No seat selection or boarding in group 1. The CC found the field but knew nothing about it. She said that the BA number was put in the FQTS field but said that it didn’t show the status. Both FF were shown in my booking but with no benefit at all. The check-in agent and lounge attendants had nothing against me showing the OWE in my BA app (I think only AS doesn’t accept this). The Avios landed in my lowly AY account as expected. I even tried to ask at the transfer desk but the agent said they have no knowledge of this field and how it is supposed to work.

Earlier I have had problems when I have booked a trip on BA.com/QR.com using my BA account and then added the flights in the AY app (I thinnitbisbveryvhandy to show all the reservations in one app). Somehow this changed where the Avios were credited. Luckily AY was able to remove those Avios and the the Avios from QR landed on my BA account.

Anyhow, I m soon AY Gold and still one year BA OWE so in the future I have no reason to put my BA Club number in the reservation.