We're on a land/sea package in September with Disney transfers for all of our ground transportation. I'll have my 3-year-old and my 18-month-old and am wondering if we will need their car seats for the Disney transportation. It would definitely be easier to check the carseats with the other luggage if we'll be on a big bus, but don't want to get stuck on a little shuttle van without the seats. My inclination is toward safety, but that means dragging the darn carseats around the boat with us until our room is ready. Anyone with advice out there?
Is it a requirement to have a car seat on the plane? I have a 5 yr. old and hadn't thought about this until I read this question.

