My ten (nearly eleven) year old still rides in a booster most of the time, but he is close to five stepping in some cars. In our primary vehicle however we are having belt fit issues. With a lbb the shoulder belt slips off his shoulder and is too low. Without the booster the belt rides up on his belly. To further complicate things, the shoulder belt attaches forward of the bight and he is skinny so unboostered the shoulder belt isn't snug against his shoulder even though it is in the right place. Is there any way to solve these belt fit issues? Changing seating locations isn't really a great option due to tether locations, rfing seats, and carpool needs.