California Codes, Code of Civil Procedure - CCP, Part 2 — Of Civil Actions, Title 4 — Of the Place of Trial, Reclassification, and Coordination of Civil Actions, Chapter 2 — Reclassification of Civil Actions and Proceedings, Section 403.070

(a) An action or proceeding that is reclassified shall be deemed to have been commenced at the time the complaint or petition was initially filed, not at the time of reclassification.

(b) The court shall have and exercise over the reclassified action or proceeding the same authority as if the action or proceeding had been originally commenced as reclassified, all prior proceedings being saved. The court may allow or require whatever amendment of the pleadings, filing and service of amended, additional, or supplemental pleadings, or giving of notice, or other appropriate action, as may be necessary for the proper presentation and determination of the action or proceeding as reclassified.