I have not tried that since Ambitions, but, I had a household with that same situation. Husband, wife, stepdaughter. Stepdaughter decided to flirt with stepdad, shocker, I did not think that they could do that. Of course he denied any passes and they had enough LTP to get "no jealousy" and "stone hearted" and I kept my eye on her. She did it a few more times too. I have not played that household in a while, but, it does happen. I have found on here, that some peoples games have things happen, that others do not.