Family court proceedings?

Here is the situation. The mother of my son wants to try and take my son away from me so we were pulled into child's court. We were not married together. She is a convicted drug user and seller, she suffers from bipolar disorder (she doesn't take her medication), she has a history of neglect and abuse toward her first child, which was why it was taken away from her and put into the system. This is her second child and my first. DCFS considers her a high risk mother. When she was pregnant with my child, she got busted for drug trafficking and was sent to prison. While serving her time, she gave birth at the local hospital near the prison and I was called to pick up my son, and he has been with me since. Since the second day of his birth. I have no criminal history but i also suffer from a mental disability and it's controllable though medication. When the dependency investigator asked me if i suffered from any mental conditions, i denied it, however it was again brought up during court by my lawyer and i again denied it. He has requested another investigator to collect my SSI medical records (which clearly says my SSI is based on a mental disability) and ask me some more personal questions, including accusations the mother made about me and my family history. I am very concerned over the fact that one of my siblings has a criminal history and i deny their existence, but they keep asking me about it. They've even ordered my mother to the court to testify. I don't understand why my sibling is even relevant to this case but they keep asking about it. I don't want my mother to lie and be convicted of perjury but i also don't want to shine my sibling to the case.