I will repost his answers here (with his permission) when he responds. 

You have my permission....

You can't just split properties into multi-family without proper permission.

But had one installed on roof without permission, too.  

A few things have to fall into place, meaning permission to subdivide and most the rest are things that can be figured out.

Investment to investment and business to business property is always permissible. 

I haven’t seen it but you’re probably agreeing that you have the tenant’s legal authority/permission to screen them.

It's increased traffic, increased wear-and-tear, increased risk of liability, increased risk of damages, and she's making money off your property.Despite that, she's already late on her first payment, she's complaining about the late fee that she agreed to in the lease, and she's making alterations to the home without permission?

I wasn't able to find anyone who had invested w/ them, but they were willing to put me in touch w/ some of their current/past investors (if they can get their permission).

It takes a lot of time and is stressful for everyone.If the house cannot be lived in (no working bathroom, no water or electricity), then you have to be permission and pay rent into a separate account.