N.Y. Relig. Corp. Law § 44
If the vestry of a Protestant Episcopal parish, hereafter incorporated, shall, by resolution, recommend that the number of vestrymen of such parish be changed to either three, six, nine, twelve, fifteen, eighteen, twenty-one or twenty-four vestrymen, notice of such recommendation shall be included in the notice of the next annual election of such parish, or in the notice of a special meeting to be held not less than six months before the time fixed for holding the next annual election thereafter, and be submitted to such annual or special meeting. If such recommendation be ratified by such meeting, the presiding officer thereof, and at least two qualified voters present thereat, shall execute and acknowledge a certificate setting forth such resolution of the vestry, the fact that notice thereof had been given with the notice of such annual election, or with the notice of such special meeting as the case may be; that the meeting had ratified the same; and the number of vestrymen so decided on. Such certificate shall be filed in the office of the clerk of the county in which the original certificate of incorporation is filed and recorded, and such change in the number of vestrymen shall take effect at the time of the next annual election thereafter. If the number of vestrymen be thereby increased, then, in addition to the number of vestrymen to be elected at such annual election, one-third of such increased number of vestrymen shall be elected to hold office for one year thereafter, one-third of such increased number shall be elected to hold office for two years thereafter, and one-third of such increased number shall be elected to hold office for three years thereafter. If the number of vestrymen by such change be reduced, such reduction shall not affect the term of office of any vestryman duly elected, and at such next annual election and at each annual election thereafter, one-third of such reduced number of vestrymen shall be elected to hold office for three years.
N.Y. Relig. Corp. Law § 44