I have seen some technical explanations here on how it is possible to do this correctly so that you BP will give you automatic access to fast track, lounge access, etc., based on your *G, while crediting to your non-gold *A account. I've tried this a handful of times now and it has never worked for me. One time it seemed the check-in staff understood what I was talking about, but the rest of the times, they either have no clue or say it's not possible to do what I ask for.

Now I do one of two things, depending on how much time I have:
- If I want to use fast track, I register with my *G FF id upon check-in (or preferably before, during online check-in or earlier). I then get access to all benefits in the normal way (automatic access to lounges, etc.). At the gate I go up to the staff before boarding starts and ask them to change my FF to what I want. Never had a problem with this.

- If I don't need to use fast track, I check-in with my non-Gold FF id (I'm switching to TK too, due to the changes to TG's program), but have my TG *G membership card ready to show on my phone for check-in (business class line), lounge access, etc. Works ok so far for everything except fast track, which are usually automated and I have not attempted to persuade staff there from allowing my access based on something other than my BP (maybe it would work, but I suspect in most cases it would not).