NJ: legacy tenant moves in mentally ill girlfriend. Options?

[Johann Jells]

I inherited a tenant in a 4U property, who I knew was on SSI for mental disability. Then a few years later he moves in his far crazier new girlfriend.  I hadn't bothered to issue him a lease, since this being NJ it's very difficult to evict someone for other than non-payment, and you cannot simply choose not to renew. He helps out with the trash and keeps an eye out, so I was cool with leaving him alone while I concentrated on the other units.

It was okay till I finished renovating a couple of the other units and created storage and laundry in the basement, where their studio apt is. This drove them even more nuts as they feel their territory is being invaded. The woman is terrifying the other tenants with her aggressive behavior.

So, does anyone know where I legally stand relative to this woman. ? She's not on the lease, I've never accepted rent from her. Can any tenant in NJ move in a roommate or partner without passing landlord approval? I didn't find anything about this in the state publication. I'm also dubious that a lease clause would even be enforceable. What if they marry? Even if you have a clause in a lease I doubt you can refuse to let a spouse in.

Any knowledge specific to NJ would be appreciated. I doubt anything from a less tenant friendly state would be useful.