Hello, I wanted to get in touch again

A quick update: We have now decided against the car seat, but for other reasons. Our daughter is of course a little bigger and heavier now than she was 3 years ago (that was when she last used the seat) and we noticed that the harness is quite tight. Too tight in my opinion for a 7 1/2 hour flight (with boarding etc. certainly 8 hours+).
My wife wanted the seat to be taken and used in any case, but I was able to convince her that it could be extremely uncomfortable for our daughter if she can move so little. However, I still believe that it can be very uncomfortable on a normal airplane seat, we must definitely try to find alternatives