In a recent case in the First Appellate District, Division Three, Court of Appeals, Fiduciary Trust International of California v. Conrad Lee Klein et. al (2017), the Court held that correspondence between an attorney and trustee-client is generally not privileged when it comes to being provided to a successor trustee. In other words, the office of trustee generally holds the privilege and when a new trustee takes the office, then that person is entitled to all attorney-client correspondence by the predecessor trustee except in very limited circumstances. Some of those limited situations could potentially exist when the trustee pays for his/her own separate counsel, out of personal funds (not trust funds), and takes steps to preserve the confidentiality of the communications.
This ruling is in line with prior rulings by the California Court of Appeals. This case directly cites the seminal case for trustee attorney-client privilege, Moeller v. Superior Court (1997) 16 Cal.4th 1124.