Originally Posted by
LiviLion
I had my AB gold number in my recent BA booking so I could select my seat of choice and get into the lounge with no having to show multiple cards and boarding passes.
Once I was in the lounge I changed it via the Finnair website and it credited to BA no problem.
OP, looks like you have your answer (and solution) here. You could also ask the service desk people in the lounge to do this for you, if the Finnair website doesn't take your fancy

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