As part of renovating our first floor bathroom, I'm going to chop out
the cast iron soil & vent pipe, and replace the relevant bits with
newfangled PVCu (via an adapter) from the room below. There is a toilet,
basin and bath connected at floor level to the SVP, with no other
connections anywhere else. I had planned on using a Durgo, rather than
through the roof at present (the 4th/5th house, end-of-row constraints
are ok in my case).

However, I think I might use Hepworth HepVO traps on the basin and bath
instead, and not bother with the Durgo at all. Assuming I do this, is it
ok to connect the bath & basin wastes to the SVP just below the toilet
branch? Or do they need to be above/level with the toilet branch?

Another point, would it be ok to use a single 40mm waste branch, and
then tee to the basin and bath, or should each have it's own branch from
the SVP?

I suppose I could just give Hepworth a call, but I thought I'd check
here first :-)

Creaky