Assuming you haven't changed things,what are the requirements for the aunt to move in? I've been playing for a bit on the beta version but she hasn't moved in yet, not sure if it's a bug or i'm not doing something to trigger it
Mom will tell you about your aunt in between days 24 - 30 and the morning after that your aunt will move in.
Can edit the days in add_aunt_introduction_actions method in random_lists.rpy.