PROB §4129: (a) In a springing power of attorney, the principal may designate one or more persons who, by a written declaration under penalty of perjury, have the power to determine conclusively that the specifie

(a) In a springing power of attorney, the principal may designate one or more persons who, by a written declaration under penalty of perjury, have the power to determine conclusively that the specified event or contingency has occurred. The principal may designate the attorney-in-fact or another person to perform this function, either alone or jointly with other persons. (b) A springing power of attorney containing the designation described in subdivision (a) becomes effective when the person or persons designated in the power of attorney execute a written declaration under penalty of perjury that the specified event or contingency has occurred, and any person may act in reliance on the written declaration without liability to the principal or to any other person, regardless of whether the specified event or contingency has actually occurred. (c) This section applies to a power of attorney whether executed before, on, or after January 1, 1991, if the power of attorney contains the designation described in subdivision (a). (d) This section does not provide the exclusive method by which a power of attorney may be limited to take effect on the occurrence of a specified event or contingency.