Regarding recording: First check the law in your state about covert recording of a conversation without consent of all parties to the conversation.
I wouldn’t worry about recording laws in this youtube age - especially for someone underage.
Just having the power in her hands of recording what may be going on will give her a new perspective on the situation - she should not feel like a victim - she will control the outcome. She can use this throughout life - it will be her teaching moment....she needs to take control of the situation for this moment and for the rest of her life. Mom won’t be there when she’s older....she needs to pull herself out of any victim-mentality she’s going through now. Learn it young.