The Finnair / Royal Jordanian trick appears to no longer work. At least it hasn't changed on the BA website. Added AAdvantage number on Finnair and saved but does not cross over to the booking when I look a it on BA. Still shows executive club number. Is there an alternate work around? Helping a family member so I told them to check their boarding pass and if wrong see assistance at gate or lounge before flying .

PS: This is a slightly old thread but decided to post here rather than starting a new one.