(a) A power of attorney executed under this Article may contain any provisions, not unlawful, relating to the appointment, resignation, removal and substitution of an attorney-in-fact, and to the rights, powers, duties and responsibilities of the attorney-in-fact.
(b) If all attorneys-in-fact named in the instrument or substituted shall die, or cease to exist, or shall become incapable of acting, and all methods for substitution provided in the instrument have been exhausted, such power of attorney shall cease to be effective. Any substitution by a person authorized to make it shall be in writing signed and acknowledged by such person. Notice of every other substitution shall be in writing and acknowledged by the person substituted. No substitution or notice subsequent to the principal's subsequent incapacity or mental incompetence shall be effective until it has been recorded in the office of the register of deeds of the county in which the power of attorney has been recorded. (1983, c. 626, s. 1.)