Highback Booster Seats that can be used with seat only?

[LyrasOmlette]

We don't have a car, so only use a car seat/booster seat very rarely. But both DC, 5 and 6, have outgrown their car seats, so we would like to replace them with highback booster seats that we'll be able to use until they no longer need them. Ideally, I think I we'd like one that the seat detaches from so that we never have to buy another. The only brand I've found that seem to do them is Graco, but we've always had Britax or MaxiCosi, both of whom seem to rate the best in safety tests.

Given how rarely we sue the seats, I'm hoping we can get something good and lightweight for around £50 but am willing to spend more.

Does anyone know any other brands that design booster seats that can be detached from the back and used separately once the child is big enough?

Thanks!

The law has changed. You can’t get just booster seats now, I don’t think. They’re high back boosters until they grow out of them.

Yes, I read about the change in law. But there are some highback boosters that the seat detaches from, so bigger kids can use just that, when they reach the right height level. But I'm thinking they might still need just the seat booster? Maybe I'm wrong though.