Platt was married twice, first to Mary Hannah Davis (1741–1761) in 1756 and had two children:[1]
Zephaniah Platt (1756–1830)
Hannah Comstock Platt (b. 1758)
In 1761, he married Mary Van Wyck Platt (1742–1809) and had 12 children including:[1]
Jonas Platt (1769–1834), who was a U.S. Representative for the 9th Congressional District of New York (1799–1801), lawyer and associate justice of the New York State Supreme Court
Charles Z. Platt (1773–1822), who was a New York State Assemblyman for Oneida County (1807–1813) and New York State Treasurer (1813–1817)
James Platt (1788–1870), who married Eliza Floyd, daughter of William Floyd, and had four children. After Eliza's death, he remarried twice, first to Susan Katharine Auchmuty, and secondly, as his third wife, to Sarah (née Breese) Lansing, widow of Bleeker Lansing and sister of Rear Admiral Samuel Livingston Breese and U.S. Senator Sidney Breese.[2]
Platt owned two slaves in his lifetime, a man named "Tone" and a man named "Cato." Tone was manumitted in 1795, whereas Cato was manumitted by the Executor of his will, Jonas Platt, in 1808, four months after his death.
Descendants
Platt's grandson (son of Jonas Platt) Zephaniah Platt (1796–1871) was Michigan Attorney General.[2]