I mentioned this same thing earlier. It just saddens me to hear when people don't use the talents or gifts they have. Misery is the worst way to live. I have been there and I felt like dying.
Dying because I wasn't in a job that valued my creativity. So I made a conscious but tough decision to take back my energy and fight to live the life of a creator.
Keep encouraging your sister. Don't stop believing in her. Be there for her no matter what and keep fanning her flames. It makes a world of difference when you have someone to support you and believe in you. I really enjoyed reading this.