I think that if they are not overly busy, which they might not be at that time of day, they will try as best they can to seat you all together. Most restaurants in WDW are accomodating like that, but of course there may be some circumstances in which they won't be able to (rare I think). Usually they do not allow ordering from the dinner menu until 4PM, before that I think it would be up to the chef. Just my 2 cents.