Harness car seat for 18kgs plus

[RainbowSarah]

My DS1 is only just 2, but about 16.5kg (he's always been on 99th centile having started at 12lb10...) DS2 has just outgrown his baby seat, and so we thought we'd move DS1 into a 1-2-3 seat freeing up his seat for DS2. However we discovered when we went to mothercare that most harnesses are only suitable to 18kgs (so according to his centile chart he'll be out of harness on whatever we buy in 3-4 months). The britax extensafix was the only option mothercare had that offered a harness for longer, but when they tested it in our car, it didn't fit right :-( Does anyone of any other seats that offer a harness for longer?

I have the two way elite linked above for dd, nearly two, who will rear face til about 4yo.

Britax xtensafix

Hi again, that's fantastic, it hadn't occurred to me to look at rear facing seats, but I guess it makes sense that the harnesses can go to a higher weight in them as they are taking different forces. I will see which I can find locally to go and look at... I will let you know what we end up with.