smoke test drain vent

After connected kitchen sink in first floor (Texas home no basement) to the soil stack which comes from second floor, I need to test. When I put drain plug on main stack outside, first level bathroom flooded, apperantly all connect together since inspector suggested me to that. Is there a way to...

I have had an issue with a sewage smell for a while now. Its real bad after a shower and only comes through the hvac duct work. I can smell a little in the laundry room which has alot of our plumbing, a sump pump pit, tankless water heater, and furnace along with the air handler. So I know the...