What can I do to influence a different behavior in 8 year old ADHD girl?

(I'm her stepmom.) She controls all her friends at school, she controls her brother, she tries to control the adults in her life. She is a very talented manipulator. When people don't do what she wants, she fights verbally and sometimes violently. She knows adults are stronger than her and so her fight is screaming as loud as she can to hurt the adults ears. When kids don't do what she wants, she will call names like "jerk" and push the kids who are arguing with her. Yesterday, when she was having an argument with her brother, she was hitting him pulling on him and running away from him (he is 9) and yelling at him. When I got to her, and took her by the hand, she was pulling away from me and trying to make me let her go so she could pick something up. (Not important enough to physically fight with me!) I don't know what to do anymore about it. I have been calm... I have been in a whisper when she yells. I have loved her unconditionally. I have been patient. I have been steadfast.