I Need help with car seats and airplanes. We will be flying this summer and I am not sure the best seats to bring on the plane. My daughter will be 6 yrs 4 months when we go (currently in a 5 point harness) and my son will be a couple weeks shy of his 4th birthday (currently rear facing but at that point I would feel comfortable switching him). We have a britax pioneer, 2 britax marathon g3, a Graco headwise, and a britax advocate click tight. They are all pretty heavy so I am thinking about whether I need to look into new seats. If I use what we have I am thinking taking 2 marathons as long as my daughter doesn't exceed the height limit or one marathon and the pioneer are my best options, but I am concerned about them fitting well on the plane as they are pretty wide seats Has anyone taken these on a plane? Should I consider a booster for my daughter (for use when we arrive not on the plane), by concern with this is we will probably be on a red eye and she may sleep better in a car seat??? Any suggestions would be appreciated.