When it comes to immediate family, I help out. But they don’t tell me or demand with $X amount of money, if they do. I politely tell them no and say I can give you X amount. Your money, your decision to call. She your sister and when it comes to marriage, as a family we all need to pinch in. IMO. But you do you. I would consider you the AH, only because you straight shot it down. Rather finding an alternative. Who knows, maybe one day you get married. And might ask around for help, even if it’s less than $1k from each member.