We're a family of 5 (and party up to 10 when friends join in) and countless times have received the 2 table reservation for Le Cellier. We have NEVER been separate. We have always been seated next to each other. Thinking back, we have never asked - it just happened. I think they want to make their guests happy so they do all they can to put you together. That's one reason Le Cellier is so popular - great mgmt team and cms.
But since this concerns you, I would suggest checking in a little early - ask to be placed together - and tell them you are willing to wait.
Hope it works out for you!