Question Carseat for Sweden. Booster recommendations? Rental shop in Stockholm and Gothenburg?

I’m long winded so I’ll just post my questions first, if that’s ok:

1. The only compact/travel high-back boosters I can find are the Graco TurboBooster TakeAlong and the Baby Trend PROtect 2-in-1 Folding Booster Seat. I trust the Graco brand, but don’t know much about Baby Trend. Do they make a good product?
3. Are there any other high-back boosters you’d recommend for travel?
5. Does anyone have experience bringing one of these boosters including the back on a plane in lieu of a carry on suitcase? Or are they too big?
7. Do you know of any dedicated baby gear rental shops (not car rental agencies) with locations in Stockholm and Gothenburg?

Background if you want details:
In June, I will be traveling to Sweden with my tall 5 year old daughter and 7 year old son, who are 45” and 54” tall respectively. And my husband, but who’s counting him I’m at a bit of a loss about car seats.

I’m not comfortable renting from a car agency but was considering renting from a stand-alone baby gear rental shop. We are flying into Stockholm and out of Gothenburg, and I cannot find any rental shops with stores in both locations.

My husband is very much against bringing their current (super heavy!) car seats. They’re both forward facing in 5 point harnesses: a Chicco Nextfit and a Britax Frontier. Both have tried high-backed booster seats and they did ok, but they prefer the 5-point harness.

I was considering buying high-backed boosters to bring with us. If we go that route, I’d love to bring them as the kids’ carry on luggage. As far as I can tell, the Graco TurboBooster TakeAlong is 16.93” wide by 27.17” tall when folded. According to an email from Baby Trend, the PROtect car seat in the folded position is 12” in length, by 20” in height, by 24” in width. For reference British Airways’ limit is technically 22” x 18” x 10”, though I’m not sure how strict they are.

That is a tough one! If it was an American airline I might recommend a lightweight harnessed seat for the younger one, but I think other airlines don’t allow as much car seat use on planes.

One common recommendation is to get a lightweight high back booster, pack the back in your checked luggage, and carry on the bottom. That way, you are assured to have a booster when you get to your destination, and if all goes well with your luggage, you’ll have your high back booster. Assuming both kids are over 40 pounds, this might be the best solution for you. Just practice with the boosters before your trip so the kids can sit properly in them and you can get them back together again! This keeps you from having to worry about carry on sizes while making sure the kids are safe. And if one isn’t great at sitting still, maybe you or your husband can sit in the back to help remind them to keep in position.

How much driving do you expect to do? Most 7 year olds do just fine with a backless booster only, unless they’re likely to fall asleep. If we’re only talking about short drives, I’d probably just go backless for both of them.

Practice beforehand so you are stuck with jet lag and a kid who won’t sit up.

Thanks for your replies and advice. We will unfortunately be driving long distances to visit family - most drives will be 4-6 hours. (We’ll be turning on some audiobooks!)

I think I’ll go with high back boosters for them both. My son has (fairly mild) developmental delays, and I think we’d both be more comfortable with a high back. I lean towards getting the folding ones and bringing them on the plane as carry-ons. Worst case scenario and they don’t allow the whole folding booster as carry on luggage, I’ll bring an extra stroller bag, gate check the backs in it, and bring just the bottoms as carry-ons. (If there’s extra room in the luggage I’ll pack the backs and just bring the bottoms as carry o a to begin with, but I rarely have extra room.)