after reading a few things and talking to some people I finally decided to ask Safe-N-Sound: if a child is over the weight limit of 22kg (crash tested weight) but under the height markers can they stay in the inbuilt harness....I even thew the figure of 26kg in as a ball park figure.
They told me that YES if a child is over 22kg (even 26kg) but under the height markers they can stay in the harness as its safer.
Response: it's unlikely that 26kg child would fit into the harness under the shoulder height marker however if they did and they are under the height marker it is safe for them the travel in

I am struggling to get my head around it.
How can they say this if the seats are tested to 22kg?? How would this hold up insurance wise??
(my sisters daughter will be over 22kg before she reaches the height markers which is why I asked)
Just want to know if someone can explain.....