Hi Taylor,
What a merry gathering you're planning! Large group reservations can be a bit challenging at many Walt Disney World restaurants, especially on a holiday, so it is good that you are doing some homework before the 180-day reservation window opens.
You will find that the character dining buffets such as
Chef Mickey's,
Crystal Palace and
Hollywood & Vine accept reservations for large parties online. A few other restaurants do as well, including Whispering Canyon Cafe, 'Ohana, Restaurant Marrakesh and Biergarten.
On a number of occasions, I've made reservations for large groups such as yours. When restaurants don't accept reservations for parties that large, my friend and I have each made a reservation for 10 at the same time. Sometimes, we've been able to combine our reservations into one large table by arriving early at the restaurant or calling in advance. Other times, our parties has been placed at tables near each other. We have done this at Boma, Yachtsman, Rose and Crown, Trail's End, The Wave and a few others.
I suggest you decide what your top choices are and try for your reservation right at 7 a.m. on the day Christmas reservations become available. You may find it easier to call Disney Dining at 407.939.3463. If there's a long wait to speak to a cast member, I'd sign search online during the wait. (I'm a proponent of the full-court press when Disney dining reservations are at stake.)
I hope that's helpful, Taylor. Thanks for your question and please let us know if you have any more questions. Enjoy your holiday with your family!
Wilma