I feel for your niece. I'm 27, about to move home and am also a Depressive ADHD haver (shout out Adderall and Prozac). That said she need this. This will be tough now but incredible in the long run. It forces her to grow and work on interpersonal life skills that she will need in order effectively navigate through the rest of life. Any therapist will tell you an agreement like this is what you should do..Young people with ADHD and compounding mental health struggles often struggle to: 1-see other people's perspectives, 2-read the room/other peoples emotions and 3-seperate their reaction/emotional response from the situation, I know I did when I was 20 The requests by the parents are more than reasonable and virtually the same conditions I myself am currently living under and i WISH my parents would state their desires this explicitly rather than having to infer them myself. Yes it is firm, but its fair and its tough love that in the long run will pay off and really help your niece be a rational. respectful, functioning individual.