Hmmm, sorry, but I don't think there is such thing as a "belief spell". People have their own thoughts and there is no person in the world that thinks the same as someone else. Instead of being frustrated with her, try putting yourself in her shoes for a moment. Is what you're saying going against any of her personal beliefs, if so, how can you communicate with her in a mature way that is easy for both of you to understand? Spells are not meant for quick-and-easy solutions like solving family problems, but they can be used as a source of energy to direct the issue which you are trying to overcome or face. Just sit down and talk, don't yell and be open to hear things from her perspective, too. Good luck.