I've got a 2002 Zafira and the middle seat has only got a lap belt. I've got 3 kids and one of them has been using a car seat with a built in harness that can be fitted with a lap belt, but this is only intended for use up until 4 years old. When we go on holiday, we need the boot space, so can't use either of the back seats. Does anyone know of a suitably large seat with a 3 point harness that can be fitted using a lap belt? My child is average size for his age. Thanks.