Nothing you can do. Let God do it. Forgive her. Pray for her. Do nothing but be kind to her. God may move her or she may be deeply affected by your opinion, whether she shows it or not. You may plant a seed in her that will take root and correct her behavior later.
I've got a similar issue. My sister isn't promiscuous, but she's come out as lesbian. She's also atheist. She's very, very liberal. She's a part of ANTIFA and she meets up for anti-Trump parties with some of her friends. Now, I'm not pro-Trump. I voted for him, but I'm not a fanboi. Every since then, our relationship has been tense. She thinks Trump and anyone who supports him in any way is evil. She stopped talking to me for three years and she's only recently allowed me to get a foot in the door. She hasn't spoken to my dad in 10 years for political reasons.
Anyway, I feel you. We've got to let God work and you've got to be personally moral. The actions of other people are beyond your control. Honor thy father and mother. Your parents aren't stupid and they aren't retarded. Lots of people are going to Hell because of their own choices. Don't be one of them.