DS1 is moving his chest clip while in the car. He did this months ago, and I explained how the seat belt needs to be clipped for him to be safe. He has gotten really defiant these past couple weeks, and today started doing it again. Today, it was as low as his waist. Is there any way I can get the chest clips to stay where they are supposed to be? He is still RFing. He is small for his age, we have a seat with very high limits, and he says he like sto put his feet up