2 cars, a toddler and baby = car seat advice

[TheCaretakerNadine]

We have a 3yr old (15.15kg), and a 1yr old. We have 2 cars so the toddler currently has joie stages in both cars.
The baby has 1 car seat -joie gem which is a newborn one but is growing out if it now.

We don't wanna buy 2 car seats so am looking for something lightweight, that can easily be transferred between cars.

Dh wants to get a booster for the toddler so the baby can use his carseats, but that isnt recommended at 3 - hes also 15.15kg.

Any thoughts welcome

How close to outgrowing the carseat is baby?
I'd just kick the problem into the future, and hopefully the oldest will have had a growth spurt before baby actually outgrows the seat.
Then go for 2 high back boosters.

They might actually be ok to go straight to a booster. I just bought a new booster for Grandma’s car, went for the Cybex T Solution, and that was 3 years old, 100cm and 15kg as the minimums. So height dependent it could work for you. Doesn’t have to be that seat necessarily, I just like it for safety and the reclining headrest, but chances are most other boosters will be similar. Biggest thing with a 3YO though is trusting they’ll sit nicely and not mess with the belt! But if the baby seat isn’t quite outgrown yet then you might be able to push this for a few months and that’ll make all the difference. Both of mine moved into a booster at around 3.5 - DS had a britax advansafix, which actually could be worth a look recommend if you want a forward facing harnesses seat for now that later converts to a booster, and the harness limit on that is 105cm which realistically a lot of kids will outgrow before 4.

when will the 3 year old turn 4 and how tall are they? I wouldn't want a 3 year old in a high back booster because I wouldn't trust them to sit appropriately and leave the belt where it is supposed to. If they're about to turn 4 then slightly less of an issue but I personally wouldn't.

How often do you use each car? If you mainly use one and could put up with moving the stages between cars, then I'd just use the 2 seats you have for the time being and see if you can get the 3 year old well into being 4/5 before you put them into a booster.

Can’t you just have one car seat for each of them and whoever has the kids drives the car with the seats in?

I wouldn't be keen on a high back booster for a 3yo at just 15kg and 100cm - they say it's better for them to be closer to 18kg before switching and 3 is quite young behaviourally, so would prefer to keep in a 5 point harness personally.

I agree the Advansafix (or Evolvafix is similar) is nice. It's not the lightest because it has isofix. And the top tether I found a bit annoying when taking in and out because it means you end up going back and forth into the boot, though you might not need to do that if your tether point is higher up on the back of the seat perhaps.

The Stages is a fairly lightweight and easy seat to transfer, so why not put one child in each seat and swap them over? Or did you want only one seat to transfer and keep the second one in place?

Assuming 3yo is forward facing if you're considering HBB - an isofix/top tether seat is worth having if it's feasible. So another solution could be to repurpose one Stages for the youngest to swap back and forth, keep the second Stages in the less-used car for the eldest and buy a new, isofix/top tether seat for 3yo to keep in the most often used car.

These are about £160 at the moment and have good safety ratings. The harness limits are 105cm and then 18kg for the Maxi Cosi or ~21kg for the Britax and Silver Cross. Then they each convert into high back booster. From 15kg-18kg is maybe a year or so.

Maxi Cosi Titan i-size (amazon)
Silver Cross Essentials Balance i-size
Britax Evolvafix (Amazon/argos)