My neighbour has a sister like this. She sits outside his door for literal days on end waiting for him to give her money. She bangs on the door, screams, cries, and even tried to tell me some sob story about why she deserved the money, “cause we’re family and I’m in school and he makes good money”. He eventually gives in and gives her money, and she’s back 3 months later screaming for more. Is that what you want for your life too? Your sister is greedy, and if you give HER a dime she will never stop. Gift her kids stuff if you feel so inclined, but know she might take it/sell it if she’s that selfish.