Then after you move in I decided to rent out one of the rooms to a stranger.

Most mortgages have a due on sale clause, so if she sells the property to you and holds the paper she's going to have to pay the existing mortgage off so she can take first position and if she's in pre-foreclosure, that's unlikely; but stranger things have happened.  

The caveat is the tenants must be comfortable being able to live amongst complete strangers.

You'll make more money renting to strangers.

@Lance Peterson I don't know your market or comfort level of having strangers in your home, but I think you would be counting on many things going right to meet your need.1.

However stranger things certainly have happened. 

Typically friends or family is cheaper than borrowing from strangers.

This is the same notion that AirBnB have overcome with their rating and review system, which now provides a safety net for people to invite complete strangers into their home in exchange for money!!!

My wife didn't like the idea of strangers raising our kids.

I came across the term "peer to peer" investing and jumped to the wrong conclusion as to what it meant...but that mistaken idea is stuck in my head.  Got no search results, so I'll ask the forums.We're are building a ...