15. The council of an upper-tier municipality, on such conditions as may be agreed upon with the council of a lower-tier municipality, may,
(a) assume any authority, responsibility, duty or function of a planning nature that the lower-tier municipality has under this or any other Act; or
(b) provide advice and assistance to the lower-tier municipality in respect of planning matters generally. 2002, c. 17, Sched. B, s. 4.