Life is all about uncertainty and how we cope with it.
Of course she can answer. "I've been accepted to X and tentatively planning to attend. I'm still anxiously awaiting word from USAFA." Done. That's an answer. Who wouldn't be satisfied with that?
Not important.
Put in a deposit. If a USAFA appointment comes, then respectfully inform the university that she will not be able to attend. Most universities are very understanding. Worst case a little money is lost.
Deciding now really only buys a handful of "peace of mind" weeks before she'd find out anyway. Is this short relief really worth it?