I am not flying with my child. Instead, I will meet my child in the destination of my flight. I have a small backpack and one carry-on luggage, which is free for most airlines. Can I carry on additionally a child's car seat? In fact, it is a booster seat. It will not be used during the flight, but will be used in a rental car in the destination city.
To be more specific, I will fly with Delta and Jet Blue this time. If checking in the booster seat would be free, that should be the best solution for me. Can I?