Is the burden of proving the validity of a trust transferred to the Padayao?

Stover also contends the court erred in rejecting his assertion the burden shifted to the Padayaos to prove the validity of the trust under the common law doctrine of undue influence. As Stover points out, the common law doctrine continues to exist alongside the statutory one: "[T]his statutory scheme supplements the common law doctrine that 'a presumption of undue influence, shifting the burden of proof, arises upon the challenger's showing that (1) the person alleged to have exerted undue influence had a confidential relationship with the testator; (2) the person actively participated in procuring the instrument's preparation or execution; and (3) the person would benefit unduly by the testamentary instrument.'" (Bernard v. Foley, supra, 39 Cal.4th 794, 800.)