California Code, Family Code - FAM § 8920

(a) A child who was adopted as part of a sibling group and who has been separated from the child's sibling or siblings through readoption by a resident of this state may petition the court to enforce any agreement for visitation to which the separate adoptive families of the siblings subscribed prior to the child's readoption or to order visitation if such agreement does not exist.  The court may order that the agreement be enforced or grant visitation rights upon a finding that visitation is in the best interest of the child.

(b) In making a finding that enforcement of an existing agreement or the granting of visitation rights is in the best interest of the child under subdivision (a), the court shall take into consideration the nature and extent of the child's sibling relationship, including, but not limited to, whether the child was raised with a sibling in the same home, whether the child shares significant common experiences or has close and strong bonds with a sibling, and whether ongoing contact with a sibling is in the child's best interest, including the child's long-term interest.

(c) As used in this section, “sibling” means full-siblings or half-siblings.

(d) As used in this section, “readoption” means the process by which a child who belongs to a foreign-born sibling group that was adopted together through an intercountry adoption is subsequently adopted by a different set of adoptive parents who are residents of the state.