I don't think she is lazy, just used to you cleaning up the housework. As the old saying goes, we depend on the mountain to eat, and we forget everything else. That is to say, because we have done all the work, she thinks she can't do it, but you can, so gradually she has a job that doesn't belong to her. You should make it clear to your sister that as a girl, you can make a plan to do a good job in hygiene and housework. Then you two sisters work together on Sunday, and then make a rule that whoever does badly will be punished for doing housework for a week. I think your sister will gradually get into the habit of cleaning up the housework.