However, this tenant seems to want to abuse your kindnesses and I would be tread carefully with this one. 

You need to consider the fact that they will likely be heavily damaged.Tenants will abuse the hell out of them so do not expect felt pads and lease language to be of any use..

Although they may offer a free estimate don't abuse them.  

Do they only check for violent/sexual crime and threats to other tenant, or is a marijuana felony usually enough to keep a tenant from renting a place to live?

What if they break up - and she decides that due to his abuse she needs to flee the home.

Instead you would want to build the units for toughness and abuse by the lower income tenants.So if you factored a purchase of 4k a door for 24,000 and then each unit needed 13k a door you would be 102,000 all in stabilized.

Those do not stand up to abuse much at all.

Some tenants could abuse the system and overuse utilities, but at least you're not paying the bill.... all the tenants are.

If it were that easy, people would be abusing the hell out of the system.

Family Member is defined as follows, regardless of actual or perceived sexual orientation, gender identity, or legal marital status:  child, parent, or grandparent; o a child is defined as a son, stepson, daughter, or stepdaughter; o a parent or grandparent includes a step-parent/grandparent or foster parent/grandparent;  spouse or domestic partner;  legally adopted son or daughter, including a child who is placed with the Borrower by an authorized agency for legal adoption;  foster child;  brother, stepbrother;  sister, stepsister;  uncle;  aunt; or son-in-law, daughter-in-law, father-in-law, mother-in-law, brother-inlaw, or sister-in-law of the Borrower.Or these other exceptions:(3) Exceptions to the Maximum LTV The 85 percent maximum LTV restriction does not apply for Identity-of-Interest transactions under the following circumstances.