Cal. Welf. & Inst. Code § 366.29

(a) When a court, pursuant to Section 366.26, orders that a dependent child be placed for adoption, nothing in the adoption laws of this state shall be construed to prevent the prospective adoptive parent or parents of the child from expressing a willingness to facilitate postadoptive sibling contact. With the consent of the adoptive parent or parents, the court may include in the final adoption order provisions for the adoptive parent or parents to facilitate postadoptive sibling contact. In no event shall the continuing validity of the adoption be contingent upon the postadoptive contact, nor shall the ability of the adoptive parent or parents and the child to change residence within or outside the state be impaired by the order for contact.
(b) If, following entry of an order for sibling contact pursuant to subdivision (a), it is determined by the adoptive parent or parents that sibling contact poses a threat to the health, safety, or well-being of the adopted child, the adoptive parent or parents may terminate the sibling contact, provided that the adoptive parent or parents shall submit written notification to the court within 10 days after terminating the contact, which notification shall specify to the court the reasons why the health, safety, or well-being of the adopted child would be threatened by continued sibling contact.
(c) Upon the granting of the adoption petition and the issuing of the order of adoption of a child who is a dependent of the juvenile court, the jurisdiction of the juvenile court with respect to the dependency proceedings of that child shall be terminated. Nonetheless, the court granting the petition of adoption shall maintain jurisdiction over the child for enforcement of the postadoption contact agreement. The court may only order compliance with the postadoption contact agreement upon a finding of both of the following:
1. (1) The party seeking the enforcement participated, in good faith, in mediation or other appropriate alternative dispute resolution proceedings regarding the conflict, prior to the filing of the enforcement action.
2. (2) The enforcement is in the best interest of the child.