We have some 2005 banked points left to use by the end of Feb. 2007. If we book a room for our friends by August 31st (the date that the points have to be booked by) and our friends change their dates of travel, what will happen to our points? Are they still good as long as they are used by end of Feb. '07 or can we not make changes to the ressie once the August 31st date passes?