Here are 3 tactics that can help make your deal work that I've discovered.

I use the standard Realtor lease agreement, which lists all the tenants that are allowed to stay in the property.

Well, after we closed and brought our rehab team in, they discovered a small door in the back of the property (covered with siding, so it blends in). 

The standard is your intent. 

They’re entitled to apply their same screening standards and wait for a tenant who meets their qualifications.Once they find a qualified tenant, and that tenant starts paying rent, then at that point your brother-in-law would no longer be responsible for paying rent.

Second does the area support rents that make sense to eventually rent it out to your standards?  

: Inventory down, prices and rents up. 2 week tenant turn over is long, 2-3 days is standard. 

I don't see any reason you cannont utilize additional financing options beyond the standard lenders. 

We have rented several places, we didn't get any sparkling appliances.We didn't miss any "bad parts"; its just some people have very high standards of what they consider clean like wash an already washed plate or spoon before using and some others would just rinse their coffee cup before pouring in their evening cup.but then you should bring it up before you sign the lease.

For example, where a duplex or quad can secured with standard residential financing, a medium sized apartment block will require things like environmental assessments, etc...