Gary - Might help to make it clear what the terms are for those not yet committed to this dinner event. My experience with these types of events, is the following:

The hotel will make sufficient food to accommodate a known headcount. If folks don't commit to attending by the "drop dead" date above, they'll probably not be able to show up, pay at the door, & enjoy the dinner with those that did commit. Really not a big deal, as there are ample eateries in Eureka Springs to handle folks that need somewhere to eat that night. We've had folks drop out of this event in the past week. And CAA8 still is far enough off that folks might be undecided whether they will be able to attend. Cancelling a hotel reservation is simple. But getting your money back for the dinner could be troublesome. Probably why folks haven't committed yet.

If these aren't the terms, then let the group know what the terms are.