The biggest cost is not canceling thus another family doesn't get a chance at the spot. So try to cancel as soon as you decide. You can do so by calling the DINE line, stopping in at Guest Svcs, at a restaurant podium or with a hotel concierge.
Any meal that takes a cc to confirm will charge a no show. You usually have to cancel w/in 48hrs to avoid the penalty. I am not sure that the penalties are the same, but they'll give you the specifics for that ADR when you reserve your time.
Hopefully you'll be able to cancel early enough or enjoy all of these meals!