I would not use a add on/ H harness. They are not safer thsn a lap sash belt.
I thought they had written the harness out of the safety standard thingy too? I know Infa say that the lap sash belt is just as if not safer then using a harness?
Yep, this. The H harness is not safer than a lap/sash belt, when the harness is not a fixed part of the seat.