I'm currently in a custody battle with the mother of my niece and nephew?

Ok, I have temporary custody notarized by a judge of my 2 year old niece and my 3 year old nephew since 2009, but I've actually been taking care of them since she was 2 weeks old and he was 5 months old. My husband and I have been providing this children including my 1 1/2 year old son with food, clothing, shelter and love of a parent. Their biological mother hasn't been in the picture until now. She had put a motion to regain custody back of the children because she has DYFS on her back because of a child endangerment case with her other 3 children. Her motivation of regaining custody back of the children I have was because she was receiving welfare benefits and cash istance for the children and was afraid of getting caught, but....on the 23rd, we had our motion hearing (which I refused to sign and she was not granted visitations rights) my attorney sent out an affidavit to the prosecutor that dealt with us that day on the 23rd, stating that she was receiving welfare benefits of the children while not having custody of them. I'm guessing the prosecutor called welfare and reported her and all of her benefits including the ones of the other 3 children were canceled until further investigation. The home she's living in now is through section 8 and welfare was helping her by paying the full rent. We're schedule for custody seminar on April 8th and if anything doesn't gets resolve that date...then the case will be sent out for a hearing in front of a judge. The mother hasn't done anything for this children. She doesn't call, to check up on them, she doesn't help AT ALL. I don't want to disrespect her in any way, but I look at her as a surrogate mother, because she dropped this children at my house and never picked them up. I stepped up and took care of them and now after all this time she wants to become the MOTHER OF THE YEAR and try to be the mother she never was to the children, just because she has DYFS on her back. A mother is a person who steps up and takes responsibilities and care for a child. Now, my questions are: Could she lose her apartment because her welfare benefits are canceled?.....I don't wish her anything bad, but would that benefit us during the plenary hearing?......I'm aware of her having the upper hands, just because she's the biological mother, but what are my chances of continuing having custody of my niece and nephew?....Oh by the way the biological father is my bother and he's incarcerated. I have proof of the her current child endangerment case (she left her other 3 children with a man that's mentally unstable and was drunk at the time while she went out drinking. The man threatened the kids by saying he was going to cut their fingers and toes and cut himself to let the children know that he was serious) and many other things she had done.