I have a couple of suggestions the Montgomery County Dept. of History and Archives has a comprehensive research library for the montgomery county area. They have a website https://www.co.montgomery.ny.us/sites/public/government/hist... and are on Facebook page https://www.facebook.com/pages/Montgomery-County-Department-...

also the three rivers website. the three rivers refers to the three waterways of central NY, the Hudson, the Mohawk, and the Schoharie. The site is predominately colonial and pre-colonial times. It is comprehensive - and searchable www.threerivershms.com
BTW, you refer to Thomas marrying Maria Clock - her name was most likely spelled Klock - the Klock family has a huge history in the Mohawk Valley.