Whenever any city, village or incorporated town may adopt this Article (together with Articles 14 and 18 of this Act), and which city, village or incorporated town shall lie within any county in which another city shall have previously thereto adopted said Articles of this Act, then in such case the commissioners of election, appointed or which may be appointed for such last mentioned city, shall also be ex-officio commissioners of election for such first mentioned city, village or incorporated town, and shall have and exercise the same powers as if specially appointed for such city, village or town.