Good morning. Needed help with this re-plumbing project. I opened up walls and figured why not right? I want to keep the same bathroom layout. Vanity and tub/shower has 1.5in drain pipes. Toilet has 4in drain and main stack is 4in. The vanity and tub/shower are not individually vented. That's the basic situation. I do have pics and a video below. My question is, should I keep the same sizes? Should I switch anything like fittings? Should I rerun the pipes through the middle of joists? I will replace with ABS. I will also add a vent for the vanity and tie into the main stack. I will also do this for the kitchen sink as it wasn't vented also. Any suggestions will be appreciated. Thanks. PS I am sistering full length joists and reinforcing framing components before redoing to plumbing.