Two part group 3 car seat

[travellingfamily]

Can you buy a group 3 car seat that comes apart into the booster seat and the high back? I know Maxi Cosi used to do one, but I can't see any currently for sale. I want one that comes apart so we can take it as hold baggage in an aeroplane more easily.

The cheap Graco one does, but it gets very bad results in side impact tests, so bad that it doesn't make any difference whether the back of the seat is attached or not!

I don't know if any others off the top of my head, I know that Britax seats stay all in once piece to discourage parents from using backless boosters.

Thank you. Found by watching the cover removal videos that the maxi cosis all come in 2 parts apart from the isofix one.