A.L.
If your daughter will have her own seat anyway it may be easier for you to have her strapped into a carseat so that she can't get loose. And that is probably less stress on you. That is how she is used to traveling buckled up too. When we traveled to seatle with our one and a half year old we checked an older carseat (our nice one stayed home, we used one that we did not care if they lost it or not). That way too you have it for your vehicle too. I do believe that if you have to transfer planes they well take care of the carseat for you. I know that we were able to have our stroller and drive it right up to the airplane door and they took care of it and then when we got off it was waiting for us again.
Safe travels to you!
A.