My 5 year old ds has spastic quad CP. He can't walk and is a wheelchair user. At the moment he is still in his "toddler" carseat, but has really outgrown it now, so we need to get a bigger one. His trunk control is not great, so he will not cope with a "normal" stage 3 booster seat. He also really needs a 5 point harness and basically needs a bigger version of the carseat he has now. Does anyone have experience of special needs (or normal, but bigger) carseats which would be suitable for a physically disabled child? Our previous carseats have been isofix ones, so that would be our first choice, but being realistic, I know we will probably have to do without that, in order to get one which will be the right size and give the right support. Any advice would be appreciated. Thank you.