Overcrowding apartments and illegal tenants without leases.

[Edgar Villanueva]

Hello BP community

I need your feedback. My in-laws own a 4 family building in the Sunset Park area of Brooklyn NY, because of his age 82, he has not kept the premises as he should. To say the least they have not properly managed the property for the last decade. All three tenants (one is unoccupied) do not have current leases and some of the tenants are living there illegally. In fact we just discovered that all three rented apartments have more people that they originally signup for. One tenant made home-made divisions in the living room and is renting that living room and the other bedroom to people we don't know. The other tenant has moved in two extra families with little kids to live there  for a total of 9 to 10 people in a two bedroom apartment. Also these people do not have current leases as I stated and we do not know who they really are as we do not have any documents on them. Our fears are in the case of a fire or anything like such I will like to know what are our rights as landlords or what could be the worst case-scenario. Please advise, we are already in contact with an attorney but I want to know if any of you have experienced this before. Thanks in advance. 

Hopeful Edgar Villanueva