Cal. Welf. and Inst. Code § 750
Whenever a petition is filed in the juvenile court of a county other than the residence of the person named in the petition, or whenever, subsequent to the filing of a petition in the juvenile court of the county where such minor resides, the residence of the person who would be legally entitled to the custody of such minor were it not for the existence of a court order issued pursuant to this chapter is changed to another county, the entire case may be transferred to the juvenile court of the county wherein such person then resides at any time after the court has made a finding of the facts upon which it has exercised its jurisdiction over such minor, and the juvenile court of the county wherein such person then resides shall take jurisdiction of the case upon the receipt and filing with it of such finding of the facts and an order transferring the case.
Ca. Welf. and Inst. Code § 750