Perhaps understand that there are some relationships that you may think they need to have that they’re really best off NOT maintaining. Children don’t need to have a father in their lives who will ultimately be toxic, even if they feel rejected by him and thus jump at any chance to be with him. YOU have to be strong and advocate for what is best. Look at the bigger picture of what patterns of behavior do to a child. They need caring adults, not necessarily someone who shares their genetic material.