After a bad water infiltration issue, I started investigating around the main problem area in our machine room. There was what appeared to be a long surface crack which ended up being a diagonal crack right through the 6" slab. It extends under a wall on top of which (I believe) rests our staircase.

My idea was to temporarily cut the bottom plate so I could open the crack (concrete saw and/or jackhammer) and pour new concrete, but there’s a stud right on top of the crack. Any ideas how to best approach this?

EDIT FOR CONTEXT: Foundation was piered/piled 6 years ago. This was the corner that had dropped the most. It’s not moving anymore. The company doind the work told us the crack was superficial and they weren’t worried about it… 😮‍💨