Cal. Civ. Code § 932

Subsequently discovered claims of unmet standards shall be administered separately under this chapter, unless otherwise agreed to by the parties. However, in the case of a detached single family residence, in the same home, if the subsequently discovered claim is for a violation of the same standard as that which has already been initiated by the same claimant and the subject of a currently pending action, the claimant need not reinitiate the process as to the same standard. In the case of an attached project, if the subsequently discovered claim is for a violation of the same standard for a connected component system in the same building as has already been initiated by the same claimant, and the subject of a currently pending action, the claimant need not reinitiate this process as to that standard.