I just successfully got my AA number added to a QR reservation using QR chat. At first they said, "Regarding the American Airline loyalty membership We
are currently unable to update the membership number over the phone or chat due to recent changes in our procedures. However, you can easily update your membership information at the airport check-in counter . I ca assist you to update known traveller numbers in the booking"

I then pressed the chat agent asking for an exception since my wife was on the same flight on a different booking and I could self-service seat us next to her once the change was made. Otherwise I wouldn't be able to and the chance of 4 seats together requested at the airport would be unlikely. They would up adding it!

The Royal Jordanian and Finnair sites did not work when I tried to do it self-service.