I have my permit for two people to enter on Cathedral Lakes trailhead on 8/7, summit Half Dome and exit 8/14 on Happy Isles/Little Yosemite Valley. Now my brother in law can't go I am wondering what is the "right" way to handle this. Does it help to call in and cancel one person ahead of time, or will it just go into the 1st come 1st served pile for that day?