if i remember correctly you all can fit in a car together on test track because i believe it seats 6 per car. I also think Dinosaur
and Splash mountain but i'm not 100% sure about any of these because it has been awhile since i've been there so i think all the rest one person might have to ride by themselves
Going 2 and 3 is going to be your best bet in most rides. Especially since you have some kids going too. Things like splash will hold 3 comfortable if one is a kid. Same w/ Haunted Mansion, and Big Thunder Mountain.
Roller Coasters like RRNRC will only hold 2 per row. So here someone will have to be alone in their row.