Looking at last year's thread and
@gyngyn's responses, schools do not see your name, nor do they see which school you have PTE or CTE'd to unless its their own. It also seems that
schools can see if people that have PTE or CTE'd to their school are still on waitlists, but again they don't know who those students are by name, nor which schools they are waitlisted at. If you switch your PTE to School B, School C will only see that you are still PTE'd to a school but won't know the name of that school so you should be safe to do so if you would like to choose School B over School A.
Also to everyone who might be losing hope, from last year's thread there was quite some movement early to mid July, and a few acceptances a week before classes started. My guess is because since these traffic rules are lame, people can hold multiple acceptances after April 30 with no enforcement of keeping their deposit at one school. As some CTE deadlines pass, they'll finally lose their spot at the other schools therefore opening up an opportunity to pull from the waitlist again. I think we are just in limbo until then, but who really knows.