According to the situation given above, to help one's sister one should first engage in a calm conversation with their parents and help them to realize the pros behind letting their daughter( your sister) follow her dreams.In today's rat race there's so little of what they might call a "safe" career. Everyone's life calls them to follow their dreams and aspirations because half heartedly she will not be able to do well in any chosen path for her. Maybe she won't be the best economically if she opens a pottery studio yet she'll live the happiest with the least regret of letting go of her dream . Moreover,who has really seen the future,no risk ,no gain...so this very risk might let her reach heights of glory which an otherwise safe path wouldn't. Finally there is no such peace as to having no regrets of not having done something, carpe diem should be the motto n helping and supporting her to follow her dreams would make them the parents they had always wanted to be.To stand by her and support her.