There are no "large rooms" that will accommodate 9 people plus 2 infants. There are vacation club villas that will hold that many people, such as the SSR Treehouse Villas and the other DVC Grand Villas, but they are expensive to get through Disney and hard to come by in December even for DVC members.
Free Dining for December 2013 is rumored to be announced on August 1st. It will probably be more affordable for the 3 families to each get their own room at a Value Resort using the Free Dining offer than it would be to try to rent DVC points for a Grand Villa (which probably isn't even available).
My advice would be to price the cost of a vacation package for each family using Disney's website. Do not include a dining plan when you price those packages but do include any park tickets you will need. When Free Dining comes out, you will pay that same price for a package but it will include the free dining plan for that resort level. You may have to shuffle bodies around in order to get the best possible price. Room capacities in most Value and Moderate Resorts is 4 people plus 1 infant. If there are more than 2 adults (age 18+) in a room, there is an additional per-night fee ranging from $10 to $25 per extra adult per night.