Dorothy,
I'm pleased to hear from you because I descend from Andrew Collett, b. 1784, son of Isaac. I've lately been working on locating Isaac geographically and have put him on the land of John Pebley at the time of Isaac's death in 1809. Now I'm trying to figure out if there's any decent way to determine if Isaac could have been married to a daughter of John Pebley.
This is the same land bought by Isaac's oldest son Abraham (your ancestor) in several transactions between 1816 and 1820.
I have located several more daughters to Isaac's father Abraham Collett and will be glad to share them with you.
Leslie