Hi! I will be staying at WL with my mom & my sister & my sister's children, age 3 years and 5 months. Our game plan is to visit a park in the morning, returning to WL about 11 ish. We plan on going to MK, AK, Epcot, and perhaps a water park. We'll have 2 umbrella strollers. My question: riding on the buses with the babies. Do we need carseats? Or will they be sitting on our laps? How crowded are the buses going back to the resorts at that time of day? Thanks!