In theory, I think it can be done. At least in the morning in Magic Kingdom. I've actually been thinking about doing this with Space Mountain and something like Speedway for my upcoming trip. Here's what I would do.
Start by booking the more popular ride, Space Mountain for the three older people. I'd refresh or wait a few minutes if you can't get the morning time slot you're looking for. Let's say you get 10:45 a.m.
Then start looking start looking for Buzz Lightyear for the other two. If it's not late enough, either wait a while or refresh. Eventually you'll end up with a time slot that at least overlaps your 10:45 a.m. - 11:45 a.m. Space Mountain. When you do, book it.
Maybe it's not just Buzz Lightyear you look for for the younger two. Maybe you're also checking on Tomorrowland Speedway and Pooh as well. That would just increase your chances of lining everything up.
After that first ride everybody is on the same schedule again and booking lightning lanes together. In my mind it would work out great. Not sure if that does a whole lot for you.
Actually, if you were park hopping this might be pretty easy to pull off by booking in the second park at 7 a.m. You can't book before 2 p.m. in the second park, meaning you have a decent chance at getting a 2 p.m. - 3 p.m. time slot for the more popular ride and you'll get it for sure for the less popular ride.