The first question would be, are they high back booster ready? At 3 children tend not to be, and I'd always recommend an extended rear facing car seat that can easily last till age 7 that is Swedish plus tested and the best carsets on the market.Can I ask what car seat everyone is using? I’ve got a 360 and my 3 year old has hit the max height already (104cm) I need to find a high backed booster seat, ideally I-size and side impact protection and something a Houdini can’t get out of, but there’s a billion different ones out there and I don’t know where to start!