Hello all...I'm in the process of expanding an upstairs bathroom that I gutted with the exception of the main stack drain/roof vent..In one corner of the room i'm installing a custom neo angle shower..directly next to that along the same wall a corner jetted drop in tub.Both of these units are on the opposite wall as the main drain, which is about 12 feet away the toilet and sink being close to the main drain....My question is.Their is no wall in the design between the tub and shower so my vent line has be ran horizontally to either an inside or outside wall before rising up into the attic to tie back into the roof vent..Can the vent line be either tied in either up stream or downstream from the traps and do I need a separate vent for both tub and shower.Also what type of fitting is best to connect both drains to the 2 inch drain line? Thank you very much for all answers..Bob