Heavy toddlers & covertable booster seats

Firstly I am sorry if this is in the wrong section, please move it if so mods :)


I am looking at changing DS into a convertible booster seat in the coming months. I am looking the the Babylove Ezy Combo as its rated high in the CREP ratings. My problem is though, DS is quite a heavy 20 month old. He was 15.5kgs at 18 months, and is probably close to 17kilos now. Its because he breastfeeds a million times overnight, he had bad reflux at the start of the year (and still does a bit now, but its nowhere near as bad), and so feeding alleviated his discomfort. So its been really hard to get him to cut down his feeds at night as he gets really distressed about it. He is slowly starting to cut them down now, but still feeds 3-4 times. We saw a peditrician at 18.5 months about the reflux, and he wasnt concerned over his weight, but I am thinking about going back to him as I am still a bit worried.

Anyway, my question about the booster seats.
The Ezy Combo says:
"Forward Facing with in-built harness.
Install with lap or lap-sash seat belt and upper
anchorage strap, (with the inbuilt harness
straps) for children 8kg to 18kg..

AND

Forward Facing with Seat Belt.
Use as a booster seat with only a lap-sash
seat belt for children 14kg to 26kg.
(Also suitable for use with a seat belt and a
Babylove ezyHarness™ Child Safety Harness
Series BL120)"

Does that mean I have to use it as a booster no matter what then when he reaches 18 kilos regardless of his age and the fact that he wont have reached the shoulder height marker? Obviously I would use the Harness thing if I had to use it in booster mode, but would that be safe enough for him?

Its really confusing, and a little frustrating that there are no seats for the heavier toddler that isnt old enough to go into booster mode :(

Ok I am now reading a manual for the Infa-Secure Rouvette from K-mart, and its only mentioning going into booster mode when the child reaches the height marker. No mention of weight at all ..... does that mean weight doesnt matter for this seat and your to go by height only? But then the Infa-Secure Odyssey manual is different and mentions weights, not shoulder heights (its the same weights as the Ezy Combo).

I just dont think those added harnesses look safe, and I dont feel comfortable putting DS into booster mode when he is too young/not tall enough. I hate how confusing this is lol

The new seats go by height.
I use the harness up to 20kgs as they are tested to 22kgs. But now all new seats have height markers to use instead.

Thanks Bellany, I didnt know that about the testing! And I saw today that the new seats are by height, but when I looked at the manuals online they were mentioning weights and barely mentioned the height markers! So thats why I got SUPER confused lol