Hi, Javin! As a mom to three, I have often worried about how we were going to be all spaced out on attractions at theme parks, but I've never really felt the same concern at Walt Disney World.
Most of the attractions have seating that will accommodate an adult and two little ones, so you just have to split the two adults among the children. With other attractions, I would have no problem putting the six year olds onto a car in front of me, while the other adult rode with the four year old.
I would say that on the attractions this arrangement might not work, you are likely to run into height requirement issues anyway. On those, you can use the Rider Switch option. That lets you wait in line one time and switch off watching the children so both grown ups can ride. You can find information by clicking
Rider Switch Service.
Have an absolutely amazing time on your upcoming vacation!