Hi, does anyone have experience of using car seats with a 5 point harness, or some other means of securing a normal seatbelt for children of 5 years and over?
DS is 5.5 and has a normal booster seat but seems to be unable to sit still in the car- every time I look round he's either leaning to the side or forward so the diagonal part of the belt is not where it should be.
I have tried constantly reminding, bribes etc to no avail 
TIA