Hey... didn't know if this was the place to ask this but I figured it might be. So this is a little colorful but would appreciate any help possible even if it's a redirection to where this question would be answered better would be lovely. So, here goes: my mother and myself have lived in our rent controlled apt. for a long time. I have have been here for the past 29 years and my mother way before that. It belonged to my grandfather who is not my mother's biological father but he married my grandma back in the 50's. Back then it was more like you inherit the child through marriage without the need or desire to document it the way things are more to the letter now I suppose. So he had taken her on as his daughter and has seen and treated her as such since.
His name as been on the lease since my mom had moved in. Building management has refused to give us a new lease for the past 5 years or so stating that they would like proof of her birth relation before they did. My mom has been in this apt. for over 40 or so years and should by law have succession rights, but laws and rules and such keep changing and it's like now she is being penalized for not being his blood daughter but has been his daughter in every shape of the word regardless of blood.
If anyone out there could send any help/suggestions possible of how to make all this work it would be extremely helpful. Sorry for the length and emotional state of this note, but it's my mom, and I would do anything I could to help her out. Thank you all so much in advance!!

I hate to say it, but the law is not concerned with what used to be. You *may* be able to get grandfathered in (pun sort of intended) but you are probably are going to need a lawyer for this.

First you need to tell us WHERE you are. Rent Control laws vary by state.

Second this is a real estate law issue so I've moved it here.

Hey Scott!! Yeah it was a little confusing on where to put my query since it involves a lot of random laws in varied fields. We are in New York City, NY. Thanks again to both of you for your responses and any help/ideas you come up with are so appreciated. We do have a lawyer who assures us we don't have anything to worry about, but my mom's a retiree on a limited income and this has been her home for such a long time, I just want to make sure all bases are covered and all options are seen/taken and such. Thanks again!!

Based on what I recall from NYC's rent control law, your attorney is correct. I'll double check it when I have more time.

Actually it only involves NYC rent control laws. That is the governing rules on succession

Thanks again!! Very helpful. We have been in legal fist-o-cuffs with building managemnet since I was a kid, so I always want to make sure there is a strong leg to stand on when it comes to defending our rights and especially my mother's rights. She's kind of old school so she's not the most educated on random laws and such. I actually looked up Rent Control and Succession laws in NYC after your mentioning and it does state "stepdaughter" as a listing of family members eligible for succession... whew! So another random question is if we have been paying our rent(which has increased) for the past who knows 6 or so years, is that right?