California Code, Probate Code - PROB § 8203

If a will has been delivered to the clerk of the superior court in a county in which no proceeding is pending to administer the testator's estate, that court may order the will transferred to the clerk of the superior court in a county in which such a proceeding is pending.  A petition for the transfer may be presented and heard without notice, but shall not be granted without proof that a copy of the petition has been delivered pursuant to Section 1215 to the petitioner and any persons who have requested special notice in the proceeding in the court to which the will is to be transferred.  The petition and order shall include the case number of the proceeding in the court to which transfer is prayed.  Certified copies of the petition, any supporting documents, and the order shall be transmitted by the clerk along with the original will, and these copies shall be filed in the proceeding by the clerk of the recipient court.