AIO about my sister getting a new promotion

My sister and I work for the same company. I should preface this by saying I’ve worked at my store for two years, and the store manager I had during that time refused to hire people, so we were constantly understaffed. She made it everyone else’s problem instead of her own. She was either on her phone or outside smoking most of the time. She made people feel afraid to ask for time off and would get angry at others for no reason, simply because she was frustrated with the problems she caused herself and wanted pity. I felt like I was going to have an aneurysm every day I worked with her. I had told my sister how awful it was to work with this manager, but she didn’t believe me, probably because the store manager was her best friend. It was so bad that the assistant manager and I had to complain to our district manager. My sister not believing me became such a problem that my mom eventually had to step in and say we couldn't talk about work anymore, because it always ended in fights at family gatherings. My mom also told my sister that she had no idea what she was talking about because she hears me come home and complain about work every night. (I still live at home, but my sister doesn’t.) This past month, the store manager quit, and my sister got transferred to my store. That now means I either have to find a new job or get moved to another store Aside from the store manager, I really like the people I work with. Moving to a new store would mean learning a new layout, adjusting to new coworkers, and making slightly less in commission every month, since I’d be the "new person" that regular customers don’t want to deal with. Right now, it’s been really hard to find a job that’s close to home, wouldn’t mean a major pay cut, and fits a part-time schedule since I’m currently in college. While I was arguing with my sister about all of this, she said it was a major pay raise for her , which is great for her, but I get absolutely nothing out of this. I don’t get a raise. Instead, I get forced to leave my store, get sent somewhere unfamiliar, or have to find a new job in one of the worst times to job-hunt. The only positive I’ll give her credit for is that I did finally get an apology. she admitted she was wrong for not believing me about how terrible our last store manager was. That was only after she talked to my other coworkers. I would also like to add that she was the one to push for my store manager to find another so she could have her job.