No minimum period of cohabitation is required.Since Bigamy is a felony in Kansas, and he wasn't legally eligible to marry, how would these properties be purchased together be divided since he was not eligible to marry.The 1st statutory warranty deed shows that a property was purchased in 2000 in my sister's name as the only buyer.

100% cannot discriminate; however, I think the best you can do is let folks know up front that this is cohabitation and anyone could rent the next room - regardless of age, gender, etc. 

Me and my wife are looking to buy a big house for co-habitation rental.

But I have been thinking about co-habitating with her again.

If the couple breaks up, are they still going to cohabitate?

The seller's previous co-habitator had offered 270K and they refused - that part was emotional.

You can choose not to co-habitate with somebody of the opposite sex.  2.  

I plan on co-habitating one house (3+1) and renting out the rest.  

Another way to find out if there are limits on unrelated people cohabiting would be to check on what defines a lodging, rooming, or boarding house in your area. 

If they had been there for a while (or if they previously lived alone/with roommates and have a record of staying in a place for a while and this is their first co-habitation together) I might consider them.