I love my sister and I love our relationship, which is why I am smarter than to allow money to get mixed up in that relationship and ruin it. If you also cherish your relationship with your sibling, I advise you to follow suit. Nothing good comes out of mixing family and money, even if your initial plan was to do something kind for each other. The sisters in this Reddit story didn't expect their relationship to end when they decided that one sister would move into the other's apartment, but tha…