Hello, I had posted earlier regarding connecting existing 3" copper drain pipe to new 3" plastic... I appreciate the reply... I have a new question... In speaking with my father, he has an existing "Double Tee" copper fitting... It basically has three 3" openings and on the top side, there is a 3" opening for the drain coming from the bathroon... Also on the top side is a 1 1/2" inch where the vent pipe connects into. Does anyone know if they make such a connector in plastic?