Cal. Prob. Code § 4235
If the principal becomes wholly or partially incapacitated, or if there is a question concerning the capacity of the principal to give instructions to and supervise the attorney-in-fact, the attorney-in-fact may consult with a person previously designated by the principal for this purpose, and may also consult with and obtain information needed to carry out the attorney-in-fact's duties from the principal's spouse, physician, attorney, accountant, a member of the principal's family, or other person, business entity, or government agency with respect to matters to be undertaken on the principal's behalf and affecting the principal's personal affairs, welfare, family, property, and business interests. A person from whom information is requested shall disclose relevant information to the attorney-in-fact. Disclosure under this section is not a waiver of any privilege that may apply to the information disclosed.
Ca. Prob. Code § 4235