Need help roughing out DWV for new double sing location

I am trying to move a double sink vanity to the wall on the left where we closed in the closet door. This 1977 floor plan didn't make a lot of sense to us so we are doing a full remodel of the bathroom and closet in the MB. I have been researching all day and the one thing I can not figure out is if I can extend the drain that is already in the wall leading to the 3" waste line. I believe I can, and if so, do I need to add a vent to the extension or will the one that will be 6+ feet away be fine? I do not want to bust up concrete and move the waste line over as this would be too costly at the moment. Any help would be extremely appreciated!

What I know so far
Drain must be at 1/4" slope
My vent pipe is 1 1/2" and the sink drains are being upgraded to 2" diameter
My waste line is 2"

What I think:
Can't move drains more than 3'6" from 1 1/2" vent (If this is correct, I will need to add a vent but do I also need to add waste line under the slab? Or is it fine to keep it in line the way it is?)

Edit: Added a diagram for critiquing. I am pretty sure that some of it is incorrect and I need to get it finished ASAP. We are moving in soon and I want it to work properly and be up to code.