Haha ;) In our larger properties, 2+ bedrooms, the long-term tenant is sometimes comfortable with staying in a shared AirBnB bedroom (shared female or male only rooms).

She will never stay in law school, and so she'll lose her funding.And once the BF/fiance moves in, he's a tenant who also has to be kicked out.I had a female law student whose "fiance" moved in, and he just sat round in the apartment playing videos all day long.  

If her son is going to live with her in that house, you can certainly get all the adults who are going to live in the rental house to sign the contract.  

LOL... but you can take It up with Johnthe ugly side of landlording.. its rare that I ever give a deposit back and I mean rare.they yell they cuss they threaten but they also do a bunch of damage.. most of them are just wind bags.now the one's that actually hand the property over and have lived there like responsible adults I give those back.. but most of my mid west stuff they never even ask. 

I don't take cosigners for grown adults.

Also what do you guys do then there is 3-4 unrelated adults that want to rent the property, do you charge extra for lets say more than 2 adults?

By the time they are adults, they are who they are, and they always will be.

It's about addressing things and solving them together like adults.

My tenants are both female, and they are friends.  

What about this (2014)New data released yesterday by the Federal Deposit Insurance Corporation, or FDIC, showed that 68 million adults in America are disconnected from the financial system in some way.