I would say that if you have a few thrill rides DH would also do, then still only FP for you and YDS (assuming the older child doesn't want to ride?)...then when you tap in ask for a rider switch pass, which is something you can use if someone is A. too young/small to ride or B. not comfortable riding but isn't old enough to wait alone for you. Does that make sense at all? Because you can easily select a few rides that all of you will get to go on, but just in smaller groups. For example, if DH would ride Space Mtn then you and YDS get FP and rider switch, which will then give a ticket for up to 3 people to return (via the FP line). Rider switch isn't available on rides which have no minimum height requirement (like Pooh). I'm sorry if this is information you already know, I definitely don't want to sound patronizing
Additionally, when you are making FP for multiple people, you can always select which members of your party you're making the pass for before selecting the ride (this assumes you have everyone linked on your account and you can "make plans" for each of them). It can be a big task if you have a large party and a long vacation, but it's pretty fun IMO
Last thing I would recommend, remember that once a person's 3 FP are used (or time has expired) each day, they have another single FP available, one at a time. If you're tapping in for your 3rd FP of the day, while you're in line you can book an additional FP at that time. I had an epic day in April where I used 13 FP in one day between the four parks due to the use of the express transportation buses, luck, and only having my oldest DS with me (DH and other four kiddos were at home).
Happy planning!
I hope that helped and didn't make it more confusing!!