The 3D drawing above is just what the house has currently (minus the existing laundry, as it's wrong): WC, Lav (31" to the right from lav trap to main stack), and Bath (left fixture in the 3D drawing). I'm still trying to draw the new basement setup, just struggling a little with the software as I've never used it before.

Looking at the fittings and things they used with the recently re-done bathroom they installed before we bought the house, I'm not sure they used all the right stuff. Might be best if I post a photo too.

Thank you for the guidance! I just want to make sure I have a solid plan that passes the first time!