However, they will need to go to court to testify about the other tenant whether they like it or not.

MANY times cities enact ordinances with illegal fees like this and they KNOW they are illegal but they also know it will take at least a few years for the ordinance to be struck down in court and in the meantime it will serve a purpose for the city.

Another search that can be performed easily is searching the county clerk of courts website to see if there are any pending foreclosures against your fiance.

Shanghai peoples court has just declared bitcoin legal virtual property and therefore protected under Chinese law

Court filings to evict tenants across Maricopa County, home to Phoenix, hit a single-month record of more than 8,000 in January.

Which in NY means like 3 months of notices and then a court case and an additional two weeks past that even if you win. 

If you evict, how much money will it cost in legal fees, court costs, lost rent (because the tenant will probably stop paying), and vacancy while you prep and fill the vacancy?

If you take them to court for violation of the lease (unauthorized long-term guests). 

There is not a court in the country where something like that would stand up and be legal.

I would imagine that once you set up a payment plan with them, they will turn on the water for the plumbers to do what they need to do.Not sure on the regulations on this but Id also see taking the tenant to court for the balance due on the water bill.Best of luck!