(1) Any county, city, village, or township may become a part of an existing authority by amendment to the authority’s articles of incorporation, adopted by the legislative body of the county, city, village, or township and by the legislative body of every other county, city, village, or township of which the existing authority is composed.

    (2) Other amendments may be made to an authority’s articles of incorporation if adopted by the legislative body of each city, village, or township of which the authority is composed. An amendment shall be endorsed and published, and certified printed copies shall be filed in the same manner as the original articles of incorporation, except that the filed printed copies shall be certified by the recording officer of the authority.