Important to know, though, is 1QS to 3 snacks must be done in a single transaction.
Also important to know is that this is not written anywhere and not done consistently throughout. Don't count on being able to do it; ask where you'd like to do it, but be prepared with back-up plan if they say no.
I tried this today at a booth. They exchanged a QS meal for three snacks. This was Cheese Studio.