Sister leaps on brother's fuck-stick and asks him not to chat about this dad

The older brother is so great with his little sister that it's almost too much. They are so lecherous that they can have incestuous sex even if their father is home. Understandably, they do it behind their parents' backs or when daddy is turned away. But most of all, the young sister is worried about her brother not telling her dad that she fucked him.