I'm adding a half-bath to on the first floor and tying into an existing sanitary line for the full bath above. Below are two designs. Design "A" runs the vent for the half-bath above the flood level of the fixtures in the full bath. Design "B" is a bit simpler on paper, but the existing riser is in an exterior wall next to a post at the point of the tie-in, so its a bit trickier to build than design "A". The sketches don't show the jogs in plan-view, which some lengths I relate may look out of scale.
I annotated the sketches with ABS pipe sizes and lengths. Blue lines are the existing sanitary, green is the new.
Are both of these designs OK? Code-wise, I'm in Nova Scotia.