Narrow high back boosters for 3 across?

[ACanOfBeans]

Preferably ISOFIX so I don’t have to worry about buckling them up when children aren’t in the car, and easy access to buckles

Do you have a budget?

BeSafe izi fix flex can fit three across but are bloody expensive. Joie Trillo may also work as rather narrow. Cybex B-Fix has a narrow base.

Also worth bearing in mind the britax KidFix SL (so ones that don’t have the side impact wind out), as the base is narrow so easy to buckle in