Legal Question in Civil Litigation in California

You can't add a defendant to a judgment after the judgment has been entered. You are correct that the defendant must have been properly served and they must have lost at trial, had summary judgment awarded against them, or have defaulted by failing to answer the summons, before a judgment can be had against them. The defendant should not have to petition the court to be removed. The court should never add a defendant to a judgment in the first place.