My step sister and her family

So me and my step sister somewhat get along, but she absolutely hates my mother since she “broke her family up”. Her mother is nice to me, and her grandmother, but she’s convinced the rest of her family that we are terrible people and always says terrible things. My mother has given her multiple chances to sit down and talk everything out, but she leaves her on read. She uses my step dad, using his truck and brining it back nearly empty on gas. Asking for money constantly for bills then buys furniture she doesn’t need. She asked for $500 dollars to get married across the country and not let my step dad walk her down the aisle, and has never paid him back for anything. Even though she has never been particularly hateful towards me it annoys me how she treats my family.