How do I convince my friend to put her son back in a booster, at least a backless one at that much. He's 8, well, will be 9 on June 30th. He's 54lbs and 51 or 52 inches tall. She took him out of the booster, b/c he rode in the middle of 2 carseats and it was hard for him to put on his seatbelt and she got tired of climbing in to help him. I was trying to tell her that if she got him one of those harmony literiders, she wouldn't have that problem, b/c of the way the arm rests are, he would be able to strap himself in with no problem. He likes riding in a booster in my van, so I know he wouldn't complain. I just don't feel he's big enough for a seatbelt only. He only meets ONE of the state requirements, and that is being that he's 8... Is there any articles or videos I can show her that express the importance of being in a booster past 8?