3 inch

Basement remodel and adding a kitchenette and washer/dryer combo. It is for the inlaws (partially disabled). Anyway, i have the 3 inch main stack right where sink will go, and the washer plumbing is approx 4 feet away. Can i do a 3 inch to double 2 inch wye to connect both? The drawing is...

Can you guys or gals help me with a code question. When I bought the house this double santee 3” ties directly into the main stack that goes to my septic, I am thinking of putting a toilet in the room and need to jack up concrete. My question is that this fitting seems improper, I was thinking I...