It is possible, though unlikely, that you could find yourself out of the FF program entirely, forfeiting all points... and standing. Airlines are paying closer attention to this. If you seach on it, you will come across people who have lost all. It is specifically mentioned as not allowed in the T&C's of OP. And yes, airlines canrecalculate your fare and charge you based on the fare current at the time if they feel you have done this on purpose.