New York Civil Practice Law & Rules R1009 - Claim by plaintiff against third-party defendant.

Rule  1009.  Claim  by plaintiff against third-party defendant. Within
  twenty days after service of the answer  to  the  third-party  complaint
  upon plaintiff's attorney, the plaintiff may amend his complaint without
  leave  of  court  to  assert against the third-party defendant any claim
  plaintiff has against the third-party defendant.

Last modified: February 3, 2019