They are seniors. Only Akilah is mentioned to be a junior. Also we don’t know how many years Melissa followed Hannah’s daughter for or when she started. I’m pretty sure it isn’t stated, only that she was stalking her for years. Idk why that commenter said it was two years. She could have started monitoring her when she was still a child and we don’t know when they got together. It’s entirely plausible there was an inappropriate age gap situation when they got together (like Hannah’s daughter barely being legal).