Need help with modifying stack for HE washer & Utility sink.

[lion_rose]

Hi All,

Could use some valued help redoing a stack to accommodate a washer and utility sink.

The plan is to have the washer, then the dryer , then the utility sink all to the left of the stack.

I believe the previous owner move the builder intended spot to make a bedroom, which I am reverting back.

I included a picture of the stack from the bottom and one from the top. It seems that there are 2 inlets into it (1 I believe from the kitchen about - top inlet, and the second lower inlet possibly from the second story washroom).

So for the Utility Sink
1) Do I hack off the left side of the horizontal 1.5" sanitary tee to connect the utility sink to

For the Washer (I assume I need to create a loop for the pipe as in the image i found on the web).
1) Do I hack above the lower sanitary tee to add a 2" long turn Y-branch
2) then create a loop (for venting) connecting back to the 1.5" abs pipe with a reverse sanitary tee.

I am not sure why they did not connect the pipe coming from the second floor to the pipe coming from the kitchen using a horizontal sanitary tee?
Or would it have been better if the upper sanitary tee be replaced with a double sanitary tee?

Many thanks for any advice.

Adrian