Seriously, if she is wearing her seatbelt, how much can she move around in that seat. The passenger seat does not tilt like the driver seat, so she will not sink into the seat if thats what you are talking about. If she has her right hand clutched around the overhead handle and has three fingers of her left hand extended up against the dash while shes in the passenger seat, it might be just a form of protest against the lack of adjustment of the passenger seat, but by no mean will she fall out of the seat.