The most common reason for amending a petition or response is to change the relief requested from legal separation to dissolution after the residence requirement for dissolution has been satisfied. Fam. Code § 2321.
The petition may be amended once, without a court order, at any time before the response is filed by filing the amendment and serving a copy on the adverse party. Code Civ. Proc. § 472.
If an amended petition is filed prior to respondent’s appearance, service on the respondent must be as for the original petition.
If the respondent has not yet appeared in the action, a copy of the filed amendment or amended petition must be served on the respondent in the same manner as that for service of summons. In re Marriage of Rhoades (1984) 157 Cal. App. 3d 169, 172; see also Engebretson & Co. v. Harrison (1981) 125 Cal. App. 3d 436, 441.
If either the petitioner or the respondent wish to file an amended pleading after both have appeared, court permission is required.
After the response has been filed, with or without notice to the adverse party and in furtherance of justice and on any terms as may be proper, the court may allow a party to amend a pleading to correct a mistake in the pleading. See Code Civ. Proc. § 473.