I'm not absolutely positive, but I think the 5 day cancellation policy goes into effect if you were to try to do this. I think (again not sure..) that if you don't modify by 5 days prior to checking in, you would lose the amount of those nights. At the very least, you would have to drop those nights 5 days before leaving, even if you could do it after checking in, so your trip would have to be at least 6 days long or longer. They have made exceptions for people that fall ill, have an emergency back home or something, but I think you do have to make any changes or drop nights, 5 days before checking in. I could be wrong. Anyone know for sure?