Oh boy. Okay I think I can tackle this from what I've read.
If school A accepts you before their own CTE deadline, you're golden. You take that acceptance, and CTE to school A. No harm, no foul.
If school A accepts you off their waitlist AFTER their own CTE deadline but BEFORE the CTE deadline of school B, you're also golden. Again, you CTE to school A.
For the more complicated scenarios: Theoretically, if you CTE to school B, you must withdraw your waitlists. Nobody is enforcing this but the schools, however. So if you decide to CTE to school B without removing yourself from the waitlist at school A, it's entirely possible that school B will just rescind your acceptance. School A will see that you CTE'd.
However, we're not entirely sure what's going to happen here. It looks like "poaching" might be a problem this cycle: where a school will offer you an acceptance with the explicit intention of taking you away from another school that you've committed to, so that they can fill their own classes.