My 5.5 year old is going to be needing 2 new seats due to school pick up. At the moment she is happy in a Frontier 85 I plan on replacing with a 90 soon. My first thought is to to get 3 FR 90s because she has Autism and likes things the same. She will be in the harness as long as allowed because she cannot sit properly in just booster mode at this age. Dh's car is my problem car as it has no latch system so no tether option. My car is a 2003 Ford Focus with Latch, she has to sit behind the driver because of a RF sibling. We do have top tether in this car. Grandmother's car she can sit in any slot, this car does have a top tether, this car is a 2005 Mercedes SUV. Dh's car is a 2002 Ford Explorer and she would most likely sit behind the driver so her sibling could ride along at times. There is no top tether which I don't like. Should I go ahead with 90's or is there a better option. I am the only one who can install a car seat and no they really are not going to learn and in the other cars except mine they will need to be removed at the last minute so reinstalled quickly so we were getting these for the ease of install.