Hi, Have you tried to get a death certificate for Henry? It might tell who the parents are. I have 3 pages of Witbecks on my web page, but no Charity b. 1803 in Greenbush. Charity was the nickname for Gertrude.
http://members.tripod.com/~JeffriesBI would be interested to know if Henry is on the 1850 census in Iowa and how you know that he was born in Schodack and she in Greenbush. Barbara