I'm in Raleigh NC. A previous post about a bathroom I'm adding to my attic and how I plumbed it is here: https://terrylove.com/forums/index.php?threads/does-it-pass.90352/ I've got it run all the way down to where I would tie it into the main stack and had a plumber I like who does a lot of work for me come out to fix an unrelated and issue and asked him for his thoughts on my work. He said he wouldn't help me tie it into the main stack because of to many violations. He specifically cited: 1. Short turn 90 not allowed on drops. 2. Only 2 bathroom units can be tied to the main stack. 3. If you go over 3 toilets you are to upgrade the crawl drain to 4” to the 1st toilet He mentioned a few other items to me that make me question if he is just being overly conservative or going by rules of thumb vs. actual code so thought I'd ask your opinions. My house has two full bathroom groups and one half bath room on it already. I'm adding another full bathroom group to the attic. This brings the total to 3 full baths / 1 half bath. I vented my new bath separate from existing vents. There are two other 2" vents on the system and while I can guess, I'm not entirely sure what vents where. My bathroom group in the attic uses a 3" short turn 90 to fit in the floor joists to go from horizontal to vertical through a wall. Drops about 9' and uses a long sweep (maybe medium?) to go horizontal (is short allowed?) about 6'. I've not tied in the drain yet to existing drains, but this runs to where I can easily wye with a 45 into an existing 3" drain from one bathroom group. After my proposed wye the existing 3" drain then wyes on a vertical with the other full bathroom group 3" drain to go into the crawl space where it picks up the half bath and carries out of the house (I need to check but not sure if this is 3 or 4". Will check and report back if it matters). Can I really not do this?