I am installing a new shower and vanity. Need to know if I can connect them to main
Stack below where toilet and bathtub are connected on main pipe.

Hi Dmoase

Yes, you should be able to do this.

Where is the sink pipe to the bathroom with the toilet and the bathtub?

What material are your pipes made of?

need to know if I can connect them to main
Stack below where toilet and bathtub are connected on main pipe. Yes as long as you run a vent for the shower. Mark's asking about the position of the lavatory drain pipe to save you from adding a extra vent for the shower, If you can connect to the lavatory drain line, (see image) you shower will be wet vented. Let us know what you decide. Tom