(a) If a person designated to serve or serving as a fiduciary disclaims a power held or to be held in a fiduciary capacity that has not been exercised, the disclaimer takes effect as of the time the instrument creating the power becomes irrevocable.
(b) If a person designated to serve or serving as a fiduciary disclaims a power held or to be held in a fiduciary capacity that has been exercised, the disclaimer takes effect immediately after the last exercise of the power.
(c) A disclaimer subject to this section is effective as to another person designated to serve or serving as a fiduciary if:
(1) the disclaimer provides that it is effective as to another person designated to serve or serving as a fiduciary; and
(2) the person disclaiming has the authority to bind the estate, trust, or other person for whom the person is acting.