California Code, Public Utilities Code - PUC § 1212

The commission at any time subsequent to the filing of the petition, and prior to making and filing its finding of just compensation, may authorize the amendment of the petition, or in case the proceeding is by order on the commission's own motion may amend the order, by altering or modifying the description of the property or interest therein, or by adding to or deducting from the property or interest therein, or by bringing in any additional party or parties, or in any other respect including jurisdictional allegations.