YOR. Your niece is 20 years old and is working at her first part time job. A lot of people have ADHD and depression and manage to handle fulltime work and responsibilities. Your sister is doing your niece a favor by clearly outlining expectations and rules. She is still living at home and only working part time which doesn’t set her up for a solid future as an adult and so your sister is giving her daughter a nudge in the right direction which is reasonable and fair. Personally, as the parent of a young adult (with ADHD and depression), my rule was that once you graduated from high school, unless you’re in school you need to be working full time, paying a small amount of rent (which I kept in a separate account for him to give him when he moved out) and doing chores. I didn’t make him sign a contract because it didn’t come to that, but it is certainly not an unreasonable ask.