If you have that much of a problem, either fuck their shit up or tuck your balls between your legs and call the police, or the housing department in the city.
As far as living in a home, I highly doubt there are regulations telling you how many people you can have in a house. An apartment is a different story, cause there are rental agreements, so unless the people renting that place told them in a contract they can only have 1-5 people, you're shit out of luck.
If I were you, I probably would have fucked up every single one of their cars, and the house they live in. But then you gotta think about karma, at least, that's what I think about, cause my car has been keyed before, and I still don't have the money to fix it, and it's been 5-6 years.