California Code, Welfare and Institutions Code - WIC § 778

(a)(1) Any parent or other person having an interest in a child who is a ward of the juvenile court or the child himself or herself through a properly appointed guardian may, upon grounds of change of circumstance or new evidence, petition the court in the same action in which the child was found to be a ward of the juvenile court for a hearing to change, modify, or set aside any order of court previously made or to terminate the jurisdiction of the court. The petition shall be verified and, if made by a person other than the child, shall state the petitioner's relationship to or interest in the child and shall set forth in concise language any change of circumstance or new evidence which are alleged to require such change of order or termination of jurisdiction.

(2) If it appears that the best interests of the child may be promoted by the proposed change of order or termination of jurisdiction, the court shall order that a hearing be held and shall give prior notice, or cause prior notice to be given, to such persons and by such means as prescribed by Sections 776 and 779, by electronic service pursuant to Section 212.5, and, in such instances as the means of giving notice is not prescribed by such sections, then by such means as the court prescribes.

(b)(1) Any person, including a ward, a transition dependent, or a nonminor dependent of the juvenile court, may petition the court to assert a relationship as a sibling related by blood, adoption, or affinity through a common legal or biological parent to a child who is, or is the subject of a petition for adjudication as, a ward of the juvenile court, and may request visitation with the ward, placement with or near the ward, or consideration when determining or implementing a case plan or permanent plan for the ward.

(2) A ward, transition dependent, or nonminor dependent of the juvenile court may petition the court to assert a relationship as a sibling related by blood, adoption, or affinity through a common legal or biological parent to a child who is in the physical custody of a common legal or biological parent, and may request visitation with the nondependent sibling in parental custody.

(3) Pursuant to subdivision (b) of Section 16002, a request for sibling visitation may be granted unless it is determined by the court that sibling visitation is contrary to the safety and well-being of any of the siblings.

(4) The court may appoint a guardian ad litem to file the petition for a ward asserting a sibling relationship pursuant to this subdivision if the court determines that the appointment is necessary for the best interests of the ward. The petition shall be verified and shall set forth the following: