The Flood is the wrong place for this kind of advice, but alas ... Think about potential consequences. If you command her to stop on threat of revealing her advances to your parents, what might happen? At the most, she becomes angry at you and stops. Problem solved. If you give in to the seduction, and wind up having sex with your [b]step sister [/b] what might happen then? Certainly a broken relationship, as well as it being really, incredibly awkward. Is that something you can live with?