Hello,
just advertising here before elsewhere in case it's of interest. Black Yepp mini with 4 adapters - 2 original for old style headsets (1 slightly hacked but functional) - 2 slimline ones suitable for a-head style headsets. Happy to help fit if that would be helpful to try it out. My youngest was on from around 6 months - as long as they can hold their heads up I think it's fine.
Seat is around £90 ish new and the slimline adapters are around £15 each. I reckon £60 for everything?
If at all interested let me know. Happy to do a trial loan.