Dear New York Tenant:
You should hire an attorney.
Regardless of the words used in the cut and paste document cobbled from the Internet, legally you are not a subtenant, at most you are a roommate, and the big question will be which one of the alleged main tenants claims you to be their roommate, because that person may face an eviction proceeding for allowing too many other persons to live in the apartment.
You on the other hand, are also out of line in bringing other persons into the apartment. The "Roommate Law" allows for a tenant on a lease to have one roommate. Multiple tenants on a lease cannot have any roommates, at all. A roommate is allowed to have their dependents, as well. But not stay over guests.
See the New York Roommate Law (NY Real Property Law Section 235-f:
So it is likely, that with an attorney, you could do real damage to the four tenants for violating the terms of the lease and renting a room out to an additional person. It may cost you money for an attorney, but fighting you and a lawyer will likely cost the four tenants thousands of dollars, and the tenants will likely also run the risk that the landlord will get caught up in the lawsuit and then seek termination of the master lease.
Your move. You need a lawyer.
The answer provided to you is in the nature of general information. The general proposition being that you should try to avoid a bad outcome if you can.
I agree with everything that Mr. Smollens has stated. In addition, beyond your legal position - you must consider the effects of your actions. Do you really want to go to court, win, and if you win, have to live in an apartment with these same people?
Litigation can be a good thing but too often clients forget the practical aspects and implications that go along with a law suit.