Legal Question in Wills and Trusts in California

The person in charge of a trust is called the "Trustee". You seem to be asking about a successor trustee. Typically when the parents are alive, they act as their own trustees unless they are no longer able to do so. During their lives the trust is typically revocable. But a successor trustee takes over when the existing trustee dies, resigns or is incapacitated (usually defined in the trust) and the successor usually signs a document acknowledging that they have accepted the job. A Trustee has a high fiduciary duty to carry out the terms of the trust. These duties include providing accountings at least annually. If you are the beneficiary of a trust and you have questions that the trustee has not answered satisfactorily, then you should talk to an attorney who can review the documents in your trust and give you some advice or assistance.