N.Y. Relig. Corp. Law § 197
An incorporated church to which this article is applicable, may, at an annual corporate meeting, change the number of its trustees to three, six, nine, twelve, fifteen, eighteen, twenty-one or twenty-four, or classify them so that the terms of one-third expire each year. No such change shall affect the terms of the trustees then in office, and if the change reduces the number of trustees, it shall not take effect until the number of trustees whose terms of office continue for one or more years after an annual election is less than the number determined on. Whenever the number of trustees so holding over is less than the number so determined on, trustees shall be elected in addition to those so holding over, sufficient to make the number of trustees for the ensuing year equal to the number so determined on. The trustees so elected up to and including one-third of the number so determined on, shall be elected for three years, the remainder up to and including one-third of the number so determined on for two years, and the remainder for one year.
N.Y. Relig. Corp. Law § 197