California Code, Welfare and Institutions Code - WIC § 379

In any action under the provisions of this article in which the residence of a minor person is determined, both the county in which the court is situated and any other county which, as a result of the determination of residence, might be determined to be the county of residence of the minor person, shall be considered to be parties in the action and shall have the right to appeal any order by which residence of the minor person is determined.