The problem, as Witzend identified, is that it really wasn't her brother's fault! My DH was put in this position. He had a scholarship to an excellent school but parental contribution was required. His sister also went to a very good school, but dropped out as she said she was fed up. She then had to contribute to the household budget.
My DH was very uncomfortable, especially as he then went to university, and his parents continued to support him. He didn't join in a lot of social activities, in order to keep costs down, and return some money to them. We also offered support to his sister when she needed it. Although she is gracious to us, I know from others that she still feels resentful. However, as I point out to DH, it would have been even more daft for him to have given up the opportunities he had. Moved off original topic a bit, I think OP has been sensible.