Keep track of what items are purely for the rental unit and what items are for both units.If it's an item that is technically for improvement of the whole house (landscaping, common area improvements, exterior siding/painting) you can only write off a portion.

They would each be putting in 200k each and I would be putting in 100k and would be responsible for all the property management, being paid by the other two on an hourly rate when responding to issues.

The cash flow from that property is close to nothing and if there are any issues with the property and you dont have the financial backing to handle it then it is going to be hard to deal with. 

Its not capital gains tax at all.So, none of what you just replied to technically works.Of course, consult a qualified professional... 

Let’s just say it’s had property management issues that have snowballed into other issues.Anybody know of an insurer that will take on a single family home that’s had 3 claims since 2021?

I laid out the issues of noise and disturbing the other tenets.

My main issue is that they will be booked to capacity (happily) in a short time.

Warrantability of properties is also another issue many investors don't consider.

No issues. 

As a matter of fact, my family moved to that location because my wife happens to work at one of those major hospitals.The issue is we didn't have an ADU as my neighbor did.