Legal Question in Family Law in California

This is a difficult position. Unless you become her legal guardian, or the parents agree to your providing a home for your niece you are at the risk of the parent taking action against you. A lot depends on your relationship to the parents and their agreement to the arrangement. If the parents agree, get a written document outlining the terms of the arrangement including length. Parents can transfer educational rights to you. However, in the absence of legal guardianship you would have limited authority over your niece if she decides the arrangement does not meet her needs. Your local bar association probably has a guardianship clinic that can provide some advice. Good luck.