Would you buy a HBB for 3yo at grandparents?

[Phalarope]

My parents have a Britax Hi Way for DD, who is 3.4, about 100cm and 16.7kg. They live bloody miles away, and am planning to visit with both DD and DS (4 months and enormous). I can't take DS's infant carrier on the train, for various logistical reasons.

My plan was to put DS in the Hi Way, which is approved from birth, and get a new seat for DD. Realistically, this is only going to get used maybe 2 or 3 times a year, for short journeys, and they'll have to store it the rest of the time, so I was considering a high-backed booster, to minimise cost and the number of car seats under their stairs over the next few years. Is this at all safe, bearing in mind it'd be fine in a few months, or do I need to suck up the cost of something like the 2way Elite? What would you do?

[dementedpixie]

I would just go with the hbb if it is for occasional use as they last longer than the harnessed seats.

[Laquila]

Depending on how big/tall she is you could get something like the Joue Every Stage, do she can ERF for a bit longer? You can then turn it round when you're ready for an HBB.

Good thing about the TWE is that it's harnessed even as a forward facing seat, to 25kg I think.

[Waggamamma]

High backed boosters can be used from 15kg, in this situation I'd say it's the best solution. You don't want to pay out £££ on a seat that will only be used a couple of times.

I got a britax high back booster for £30 in morhercare.

[Phalarope]

Thanks. Practical bit of me says HBB, but the other bit thinks I should probably keep her rear-facing at all times until she learns to drive. I'll take a look at that Joie seat.

[BertieBotts]

Yes, I wouldn't have a problem with this. She's over 15kg and it's not all the time. As long as the seat fits her well they say that from 3yo there's not much in it.

The only other thing I'd suggest - which I'm sure you've already thought of - could you take DS's infant carrier on the train attached to a pushchair? Or I'm wondering if they could borrow an infant carrier from somewhere for this trip, and you can keep an eye out for deals and get a really good HBB to leave there for next time.

[AliceMum09]

No - a child needs to be at least 4 years old, and ideally older, before they are safe on a high backed booster using the adult seatbelt. It's to do with the development of the pelvis, which happens with age not weight. This link explains it Plus the child needs to be able sit relatively still and stay upright within the seat for the whole journey and not start putting their arm over the top of the belt or trying to unfasten the seatbelt.

[BertieBotts]

The info in that link is misleading. Seatbelt syndrome is caused when children wriggle forwards and slouch in a booster seat, usually because their knees don't quite reach the edge of the seat which makes them uncomfortable. They slouch and wriggle forwards so that their knees bend over the corner of the seat, which causes them to be in a suboptimal position for the seatbelt. You can discourage this by placing something for them to rest their legs on in the footwell such as a suitcase or box.

Or (as my 8yo has told me he does in a cushion booster ) because it's "fun" to push the booster forwards and sink down behind it. (Note, they can't do this in a HBB, there's no gap).

It might be that the leg length and the pelvis thing occur at around the same time, but there's no actual evidence about the iliac crest being responsible for car seats failing. It's a theory, that's all.

[Phalarope]

Well, I bought a HBB, it fitted her well, and she sat beautifully in it (having been given warning of the riot act if she wriggled). She's now a bit cross at being back to rear-facing at home, which is a slightly irritating consequence, but overall all good - thanks for the advice.