If you would like to debate this further, we can take the discussion offline or you can start a separate thread.

You pay the plumber directly - your GC still recommends him - you write up a separate contract that states he will get xx% now and xx% every week - or you could pay xx% for each specific plumbing task that needs done (this will also incentivize him to stay on schedule)

Turns out I pay taxes for the both lots together and they can not be spilt even tho my neighbors on both sides have their lots split and pay separately.

If he is vacating all of his warehouse or if the sublet portion is demised/separated from the rest it is much easier.Please let me know how I can help.Thanks,Phil

On multi family, whatever is metered separately.  

There's also a nice size garage on the property that I would be using for my vehicles I store, if I cleared it out at some point, that could be rented as well, possibly could look into a separate meter, garage has its own driveway its separate from the home.  

The owner talked to the city and the parcel is not big enough to split these 2 homes into 2 separate parcels.  

Unfortunately we were planning on doing all of this in July but his current contract is up in mid-April 2017 and we haven't made any decisions whether he will re-enlist, extend, or separate.  

My triplex is actually 2 units in the main house and a carriage house, so I insure them separately for liability.

I just looked at a 6-plex where one of the units is a separate above-garage unit.