So I was with a friend last night and we were going to run some errands, she has a son who will be 3 this week and my daughters car seat was already hooked into my car (my daughter was not with us), and I had suggested since we were taking my car and our kids are the same size she could just put her son in my daughters car seat. She responded with we can't use mine because her son doesn't like the harness and he uses a booster. What the hell?! Is that even legal to put a two year old in a booster seat?? And why even give him the option to use a booster??