Daughter miserable at BM's house

[kuttn]

I have 3 children ages 16,12, and 7.  I am the NCP.  This weekend my children came to stay with me.  I had a long talk with my 16 year old daughter.  She is basically the "mother" at BM's house to my other two children.  She said that BM is never at home and that she (my daughter) does all of the cooking, cleaning, and helping the other two with school work.  She said that when BM is actually home, she invites her BF over and doesn't spend time with them.  She told me how miserable she is at her mother's house and how she wants to come live with me.  She does not want to leave her brother and sister in fear that no one will take care of them.  She willingly told me that she would testify against her mother if needed.

My first question is what is the age in Alabama in which a child is old enough to decide which parent they want to live with?  My other question is would the judge actually listen to what my 16 year old daughter has to say or do I need actual "proof" that my children are being neglected?