Reply to My Step-daughter makes me anxious

This sounds like me. Me being your stepdaughter. I hated my father because I felt abandoned by him and his love when to my stepmother who I felt didn’t love me either. Your stepdaughter is a child. Keep trying to understand where the anger she has is coming from. The fact your asking for advice means you do care. Don’t stop caring, keep trying. Try to get her father involved. Don’t outcast her. It’s probably already what she thinks she is feeling.