This will be long. I’ve organized a few large trips with my family. The largest being 23 family. It sounds like you have some of the same issues we did. All trains need a conductor and you are it. Plan the trip as you would for yourself and your own family. Everyone else can be passengers and chose what stops to get off and on at. Unless you live with these people 24/7 at home you will not want to virtually live all day with them in a park-which a park can bring out attitudes as the day wears on or someone wants to throw a kink in the plans.
You will NOT able to make everyone happy at all times.
Plan a non-park day so everyone can take a break. Some people might opt for pool time, while others go to a park to either catch up on what they missed or they know they’ll want to spend time at or sleep.
You stay out of as many $ discussions as possible.
People have different parenting styles. So stay out of that one.
Not everyone will want to ride all of the exact rides which makes fastpasses very difficult. Family A wonders why got xxx 1st tier and not xxx. So get a top 3 list from everyone.
Not everyone will want same meals. Example boys don’t want to do princess meals or some people just don’t want to do one.
What worked best for us was a general plan of attack. It sounds like you might need one big newsletter now in order to get peoples opinions. I sent monthly ones out since we had over a year to plan. First newsletter for me was accommodations. I explained the different levels, any special offers, and for them to have a plan b hotel in case your their choice isn’t available. Then make your own.
The remainder were;
meals-what meals would you like to do ranked 1-3 and what meals don’t you want to do 1-3 and would not join the family for
and with tips and tricks for eating cheap in the park;
what are some non-park activities
overall touring style: are you a rope drop family or sleep in family? Do you expect to stay late for fireworks? Will one of you ( for each family be willing to be the parade or fireworks)
So the “general plan” which was shared with everyone: meet at xxx point INSIDE the park at xxx time after rope drop; when where meals are-around late breakfast or early lunch ( those that sleep in can decide if they want to meet you there to eat or meet after meal (after all, they’ll know where to find you); where and what time fastpasses are (again-people can catch up to you there); if possible what time and where for a second meal; where parade/fireworks “sitter” should meet and what time. If you don’t send a representative we can’t guarantee a spot close by will be free if there are any shows with a specific time plan ahead which show you are going to and what time (again-they will know where to find you)
You will need to link all
MDE accounts together.
If you are using your credit card to hold all ADR’s then ask everyone to send you a deposit equal to the no show fee which you will give back to them at a restaurant WHEN they show up for that meal.
Send out final plan as soon as you are done and gently let people know that you hope they will be able to meet together as a group at one of the times listed. And that they are free to adapt it to fit their family’s needs.
Remember

lan “your trip” and everyone else can choose what parts of it they’d like.
Wow-this got really long. Sorry about that.