New York Consolidated Laws, Civil Practice Law and Rules - CVP  Rule 3025. Amended and supplemental pleadings

(a) Amendments without leave.  A party may amend his pleading once without leave of court within twenty days after its service, or at any time before the period for responding to it expires, or within twenty days after service of a pleading responding to it.

(b) Amendments and supplemental pleadings by leave.  A party may amend his or her pleading, or supplement it by setting forth additional or subsequent transactions or occurrences, at any time by leave of court or by stipulation of all parties.  Leave shall be freely given upon such terms as may be just including the granting of costs and continuances.  Any motion to amend or supplement pleadings shall be accompanied by the proposed amended or supplemental pleading clearly showing the changes or additions to be made to the pleading.

(c) Amendment to conform to the evidence.  The court may permit pleadings to be amended before or after judgment to conform them to the evidence, upon such terms as may be just including the granting of costs and continuances.

(d) Responses to amended or supplemental pleadings.  Except where otherwise prescribed by law or order of the court, there shall be an answer or reply to an amended or supplemental pleading if an answer or reply is required to the pleading being amended or supplemented.  Service of such an answer or reply shall be made within twenty days after service of the amended or supplemental pleading to which it responds.