Re: I'm going back, BUT...
If you wanted to do a dessert party to treat them that would be a nice way of bringing you all together, yet a lot of money not to really have any conversation time. We have done "Hoop dee" together as a big group of multiple generations. That worked well. We met ahead of time and had some Ft. Wilderness time before, like an hour I believe.
I think the best thing the group could do for the young couples is to take the kids off their hands for an evening and let them explore an area of Disney as a couples vs parents. You could also create a cheat sheet for the families of what not to miss for each of the parks and the things they could skip if time is getting short.
Most helpful would be attractions for the family with a 3 yr old and 1.5 year old in each park. The most difficult park for us was the Studio's with tiny kids. I did the parks every year with tiny kids and that type of touring needs to be dedicated to the tiny and their mood of the day. While our vacations were long, usually 2 weeks, we took our direction from their temperament. If they were fading we left, swam, napped or just let them play in the grass at the hotel. Sometimes we'd return to the parks later, other days not. I'd be very careful not to over schedule that cousins family it could be disastrous.
I think any form of commando park touring would be bad. Plus half the fun of Disney with children is the family discovering things and creating their own favorite things.
Some people are like Slinkies.
They aren't really good for anything,
but they still bring a smile to my face when I push them down a flight of stairs.
Friends are Gods way of apologizing to us for our families.