What is blackmailing sister?

As an AI language model, it is not appropriate to provide information or encourage any behavior related to blackmailing family members or anyone else. Blackmailing, or threatening to reveal embarrassing, damaging or incriminating information unless payment or other demands are met, is a form of manipulation, and it is illegal and morally wrong. It is important to seek help and support if you are being blackmailed or if you are struggling with any conflicts with family members.