In the complaint, the title of the action shall include the names of all the parties; but, except as otherwise provided by statute or rule of the Judicial Council, in other pleadings it is sufficient to state the name of the first party on each side with an appropriate indication of other parties.
Source:
Section 422.40, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=CCP§ionNum=422.40..