N.Y. Estates, Powers & Trusts Law § 11-1.11
purposes
(a) Unless expressly prohibited by the terms of the instrument creating an express trust, the terms of the trust instrument shall be deemed to include the following provision granting the trustee, which term as defined in paragraph (h) of this section may mean the executor or administrator, a limited power to amend: "The trustees shall have the limited power to amend the administrative and other provisions of the trust which have no significant dispositive effects within the meaning of paragraph (i) of this section on an interest described in such paragraph, by an acknowledged instrument in writing, in order to:
(b)
(i) An amendment pursuant to paragraph (a) of this section shall be conclusively deemed to have "no significant dispositive effect" if the difference between the actuarial value determined as of the effective date of the amendment