Note on Joseph's findagrave states he married Lydia Stewart in Shelburne, Mass.
from his findagrave page:
NOTE: Variant spellings of the name are McKown, McKowen, McKoen, and McCowan.
He married, first, about 1756, Hannah Clark. She was born about 1736 at Worcester,MA, a daughter of Matthew Clark and Jennet Bothwell Clark. She was killed by Indians on Mar 20,1759.
He married, second, at Shelburne,MA on Feb 23,1775, Lydia Stewart. She was born about 1747, a daughter of Charles Stewart and Mary Ayres Stewart of Colrain,MA. Lydia removed to Ohio in 1812 along with her daughter and son-in-law.
By his first marriage, he had one son who was captured by Indians, taken to Canada, and never heard from again.
Children(by second marriage): Hannah McKeown Rogers.