NY Dom Rel L § 81 (2021)
2021 New York Laws DOM - Domestic Relations Article 6 - Guardians 81 - Appointment of Guardians by Parent.

§  81.  Appointment of guardians by parent. A married woman is a joint   guardian of her children with her husband, with equal powers, rights and   duties in regard to them. Upon the death of either father or mother, the   surviving parent, whether of full age or a minor, of a child  likely  to   be  born,  or  of  any  living child under the age of eighteen years and   unmarried, may, by deed or last will,  duly  executed,  dispose  of  the   custody  and  tuition  of such child during its minority or for any less   time, to any person or persons. Such  surviving  parent  may  appoint  a   guardian  or  guardians  of the person and of the property of the infant   and in making such appointment shall not be limited to  the  appointment   of  the  same person or persons in both capacities. Either the father or   mother may in the life-time of them both, by last  will  duly  executed,   appoint the other the guardian of the person and property of such child,   during  its minority.   Either the father or mother may in the life-time   of them both by last will duly executed, and with the written consent of   the other duly acknowledged, appoint the other and a third person to  be   the  guardians  of  the  person  and  property  of such child during its   minority, and in making such appointment shall not  be  limited  to  the   appointment  of  the  same  person  or  persons in both capacities. Such   consent must have as part thereof a sworn statement that the  consenting   parent in so consenting, is motivated solely by the welfare of the child   or  children,  the  guardianship of whom is the subject of such consent,   and that such consenting parent has not received and  will  not  receive   any  consideration  for such consent, and such consent may be revoked by   such consenting parent at any time prior to the death of the  other,  by   filing  in  the  office  of the county clerk of the county in which said   other then resides, a written revocation of such consent, subscribed and   acknowledged by the person so revoking, with proof of service of a  copy   thereof  on  such  other  parent in the manner provided for service of a   summons. An appointment of a guardian of the person and property  of  an   infant  made by duly executed last will of his father or mother shall be   valid and effective if at the time the will is admitted to  probate  the   other  parent  shall have died or the surviving parent be an adjudicated   incompetent. If both parents die under  circumstances  which  render  it   difficult  or  impossible to determine which of them died first and both   of them left last wills appointing the  same  person  as  guardian,  the   appointment  shall  be  valid  and  effective. If both parents die under   circumstances which render it difficult or impossible to determine which   of them died first, leaving last wills appointing different  persons  as   guardians,   the   surrogate's   court  shall  determine  which  of  the   appointments will best serve the welfare of the child and issue  letters   of  guardianship  accordingly. If at any time during the minority of the   infant the surviving parent becomes competent to serve as  guardian,  he   may  apply  to  the  court  which  issued letters of guardianship to the   guardian appointed by will for a decree revoking such  letters  and  the   court  shall  on  such  application make such order or decree as justice   requires.   A person appointed guardian in  pursuance  of  this  section   shall  not  exercise  the power of authority thereof unless such will is   admitted to probate, or such deed executed and recorded as  provided  by   SCPA 1710.