We have just put Cairenn into a Safe n Sound Peagasus Booster seat.

She is fine with the seat belt - but she knows that she is cactus if she takes her arms out!!

The seat we took her out of was the Safe n SOund Maxi Rider and it will take kids up to around 24kg or so (don't quote me on that though! Not quite sure of the max weight). It connects to the anchor point and has a harness. Only moved her up one as we need to move Liam in order to give bubs the newborn seat! WOW are we going to have a tight fit across the back of the Fairmont with 3 seats!!

I don't know if you can get a booster that connects to the anchor point - maybe have a look on the safe n sound website or the choice magazine website is another good place to look.

Best of luck