So the upshot is that
JOHN & ELIZABETH BRINKERHOFF VAN VLACK's children included:
Henry Van Vlack b. 19 Nov 1773 d. 10 May 1812 bur. Poughkeepsie, NY m.Polly Vantine
Elizabeth Van Vlack b. 19 Sep 1779 d. 1853 m. 13 July 1796 Cornelius J. Luyster
HENRY & MARY SLOOT VAN VLACK's children included:
Henry Van Vlack b. 3 May 1778 d. 1859 Marysburgh, Pr. Ed. Co., Ont m. Catherine Palen
Elizabeth Van Vlack b. 16 Sep 1772 m. Charles Townsend
MARY SLOOT VAN VLACK married 2ndly between 1790-1794 his 2nd m. Obadiah Cooper of Fishkill, NY and Hallowell, Ont.