A question, a couple of comments, then my experience
Am I reading right that lodging is on you via your points?
22 is a lot of folks for all to make a commitment 2 years away makes it more challenging.
If you are treating on your points, then I would stress about a month before booking that the commitment needs to be racheted up a notch (blood contract, car keys as deposit, etc) due to the point cancellation hassles youre subject to.
Emergency cancellations only and get agreement on the definition of emergency.
Thanksgiving is one of the most crowded times in WDW keep that in perspective
We had a group of 16 in Dec 2003 all together in WDW to celebrate our DD's 16th Birthday. The trip was planned before we became
DVC members so we had 5 rooms at Coronado Springs. Couple of hiccups, but overall it was a great trip
What worked well
Rough plan on daily together activities; Starting park; one meal together (usually lunch or dinner)
Cell phones a must for most in the parties; for plan changes meeting up, etc.
Lots of freedom people came together and went apart fairly naturally without any problems. There were lots of personalities and this helped avoid any conflicts
What could have been better
I would not recommend a group meal the first day. Our group came from different time zones and schedules. Over half bailed on our first night dinner.
Also, only one room was ready when we most arrived, 14 people hanging out in a Moderate room for an afternoon is not the best way to start a trip. It was a little cool or else a lot of us would have been at the pool.
As stated above, we loved the freedom, but If I had to do it again, I would have set up a couple more times where we were all together, maybe for a night time show or attraction(s)
We also failed to get an entire group photo, we were scrambling at check out day to get some groups together before the shuttles came.
I like MDMMIMs suggestions about planning and communicating frequently before the trip. Also the welcome itineraries are an excellent idea
It was a lot of work, but so glad we did it. About six weeks after the trip, we had a tragedy and lost my wife's sister that went with us in a car accident.
Best to you and your plans,
G4L