I'm in Chicago and was just curious where your 4-flat is located here?

I also have been talking to a property manager and asking for insights/advice for the location. 

Central location of everything for you, not having to keep track of things in multiple places.

I would start with the Fair Market Rents (FMR) in the county where the property is located and use that as a basis to negotiate from there.Thanks Jaycee, are to referring to the HUD website? 

These were custom homes & when the subdivision grading was done we did not know the size of the homes nor their driveway locations.

You could offer to split it 50/50 or have them pay, but I'd make sure it is professionally done and the vent is put in a good location. 

You are becoming distracted and diverting your time, energy and resources away from where it should be spent which is locating and acquiring good real estate and then managing it well. 

I'm Christian Campos, a private money lender and real estate investor from Los Angeles, CA.Where are you located in California? 

Location matters.

If entities are disregarded, you can keep up with more than 1 in a single QBO account using the location/business feature to keep track of them separately.