Hi Mary,
How fun to be planning a trip with a larger group! I think I can offer you some tips to find and secure the dining experiences that you want.
I suggest that you start by heading to
Disney Dining online and searching for places that you would like to dine. For a larger group such as yours, including many children, buffets may be a great place to start. I checked and was able online to find reservations for groups of 12 at some of my favorite buffets at Walt Disney World, including
Boma - Flavors of Africa at Disney's Animal Kingdom Lodge and
Trail's End Restaurant at Disney's Fort Wilderness Resort. Sometimes with a party this large you might need to split into two tables; however, with 12 guests I think that it is likely that you would be seated together, and if not, that your tables would be very close to each other. I recently dined at
Biergarten Restaurant with a party of 11 guests at one table, and we had a wonderful time! If you are having trouble finding reservations for your party at the time and restaurant that you want, call Disney Dining at 407-WDW-DINE (407-939-3463). A cast member there will be able to help to see if what you want is possible.
As to quick-service dining, I think that you will be fine at any of these locations. Simply head on it, order your food, and find a table. Again, you might find that there is not a table large enough for your whole party at all locations; however, you will likely be able to find tables near to each other.
Please do let us know if you have any further questions, Mary!