Chilf Support for 18 year olds?

Hi everyone - I've got a question for anyone who can help.. My boyfriend's parents divorced about a year and a half ago. His parents have two kids together (my boyfriend, 21, and his sister, 18). Ever since the divorce, his mother has been draining his father dry of cash. I don't know the specifics, but she managed to get her hands on his pension, and more than half the sale of their house. ...