Our sister is the world's most annoying person. She always has to be right, which means you always have to be wrong. Whatever you say, she will come back with either "Well, you say that, but..." or "But on the other hand...". If you come prepared with evidence, or quote experts, she'll say she already knew all that, even though up to that point she will have been saying, and doing, the exact opposite. She thinks she knows how to run our lives better than we do (even though we're all functioning adults) and constantly complains about and criticizes us to one another, and her friends, behind our backs. She's 73 - is there any hope whatsoever that we can get her to stop behaving like this at this point? She lives alone, so we don't want to cut her off, but she's driving us crazy.