California Civil Code Section 1692
Civil Code section 1692 recognizes a contract may be "rescinded in whole or in part."
Upon such rescission, "any party to the contract may seek relief based upon such rescission by (a) bringing an action to recover any money or thing owing to him by any other party to the contract as a consequence of such rescission or for any other relief to which he may be entitled under the circumstances ... . ... If in an action or proceeding a party seeks relief based upon rescission, the court may require the party to whom such relief is granted to make any compensation to the other which justice may require and may otherwise in its judgment adjust the equities between the parties." (Civ. Code, 1692.)
See Snelson v. Ondulando Highlands Corp. (1970) 5 Cal. App. 3d 243, 258 84 Cal. Rptr. 800 "In an action predicated on fraud, the fact that the parties cannot be restored to the exact status quo ante will not prevent a court of equity from granting rescission, especially in the light of section 1692 of the Civil Code. Exercising its equitable powers, the court can adjust the equities of the parties and grant such relief as will achieve substantial justice under the circumstances of the case presented to it."; cf. People v. Superior Court (1973) 9 Cal. 3d 283, 286 107 Cal. Rptr. 192, 507 P.2d 1400 in absence of statutory restrictions, "a court of equity may exercise the full range of its inherent powers in order to accomplish complete justice between the parties, restoring if necessary the status quo ante as nearly as may be achieved".
Moreover, to the extent defendants viewed the injured workers as indispensable parties, they were required to object by demurrer or assert nonjoinder of a party as an affirmative defense and move to dismiss or to compel joinder. (See Code Civ. Proc., 389 joinder as a party, 430.10, subd. (d) demurrer.)