Originally Posted by
gonzalesflyer
Yes - that will work fine. The only things you lose out on would be slightly higher chance of an op-up and better treatment in the case of irrops... I have read that some airlines even allow you to enter two FF numbers on your booking - one for benefits and one to which miles are accrued. I'm not sure how common this is though...
Actually no, if you hand in your *G card at checkin, the agent will change your FF# to the one on the *G card. Same thing with lounge access, many airlines now will just scan your boarding pass to see if you qualify to go in or not, if their computer show you are *S, you wouldn't get access, so then you hand in *G card, they will change your FF# to the one on the *G card in order to bill the airline you are *G with.
The only thing you may get away is at boarding.