I am putting in a double sink vanity and took the drywall down to start the plumbing. There is a three stud corner for a closet wall on the other side of the wall, as shown in the picture. I want to connect the sink drains and vents together in the wall cavity. I would like to drill holes through the studs and then cut out blocks from the stud oriented 90 degrees to the wall studs in the two places where I want to pass through the pipes (near floor and 6+ inches above vanity). All walls are non load bearing. Will this pass inspection?
If the parallel 2x4 is just there as a nailing edge, then yes, you can notch it safely without concern.
If you notch rather than cutting a hole, you might be required to put these stud shoes in. Might not be a bad idea even if you cut a hole in the center. stud shoe