The agent, a fiery German lady going after the owner, berated the owner, threatened to sue him if he doesn't accept us as buyers, and the deal was signed off that night.An explanation.

You'll probably want to do some more digging on these tenants before accepting them.6 adults and 4 kids in a 4/2 home is a red flag itself.

Tricky, to get people to move in, it would need to be accessible to transportation, town...but the city has not accepted them so much legally as a living space.  

Tell them it's mandatory.Make sure you are named as additional insured to protect your interests but also if they let the policy lapse you will get a little post card in the mail from Lexus Nexus or a similar company saying the policy is lapsed or canceled.For those that allow pets - have them get a renters policy that does not have a dog bite or dog breed exclusion.

If you wouldn't accept the same application for a new resident, would you "let it slide" with this resident? 

you might go and see 25 properties and make 3 offers and get 0 accepted. 

Fortunately for us, our offer was accepted immediately.This was at a time when we were competing against buyers who were scarfing up Cambridge property with cash offers well above asking price.

My husband and I had an offer accepted on our first duplex.

This sounds like a pre-existing defect so you will have to review your insurance policy but I am guessing there will be an exclusion.

Now, whether we can actually get that offer accepted is another story.