What power does a mentally unstable trustee have over estate

  You use the term "trustee," which contemplates that your father created a trust.  The trust can be within the will itself or a separate instrument.  The first  step is to review the actual instrument that gives your sister some "power," (and believe it or not, that is a legal term in this context) and determine the extent of the power.    Since thankfully your father is still living, depending on the type of instrument that gives your sister power, it is possible that it can be changed prior to your parents' deaths.  If it is an irrevocable trust that may be more difficult.     If she is a trustee over money that you will receive under the trust when your parents pass, it depends on the schedule of disbursing the assets.  A true trustee who abuses her power, or fails to exercise the power in accordance with the trust, can be removed through legal process.  That is why if dad can make changes now it will be easier in the long run.   If you have access to the will/trust, I suggest you review the documents with an attorney who can then give you a more complete answer.    Please let us know if we can assist you further. Kind regards, Cindy Vova The Law Office of Cindy S. Vova, P.A. 8551 West Sunrise Blvd., Suite 301 Plantation, FL 33322 954-316-3496 info@vovalaw.com