If you cancel, the spots can be added to another trip, if the other trip has room to expand.
If I understand it right, there can only be 125 people launch per day. It goes up to 150 or 175 in oct, when the commercials stop using their allocation.
So, if all the spot are "sold", and someone cancels some spots, a TL with a "big permit" (19+) could add up to 25 total, or a :medium permit (12-1
could add up to 18 total, or small up to 8. You will not be able to turn a medium into a large, if there are already 3 large ones or a small in to a medium, if that quota was already filled..
Also if you tell her when you cancel, you can defer your permit fees for use in OCt only.