I was wondering if you ever found out any further information on those you've mentioned in your query. familysearch.org has their marriage information as well as the information of the death of one of their children, Charles.
In addition, I found a family over there with 12 children, all of whom were born in Orange, Vermont.
Our Daniel has named several of his children the same names as those who might be his siblings, specifically, Charles, George & Mary, and if Daniel's son, Daniel, often went by David, then there's a David too.
With there being a George born in 1809, it left me wondering if possibly George is Daniel. I.E. George Daniel or Daniel George.
I've found nothing concrete yet with regards to Mercy Pollard. :(