I have gotten most of my information off of the FamilySearch websight. It is very exciting to think that we're related to the family from RI. Unfortunately, I'm not sure if we're related to them. I saw on GenForum where someone posted that Nehemiah was born in England and emgrated here with his brother Asa. But also, I found on Genforum that he was born in Prince William County, VA about 1731 and was a Patriot in the Revolutionary War. His son Benjamin was a Private in the 1st. Virginia Regiment. So, now you can see my confusion!
Also, I can't seem to find any info. on Abigail Grigsby. Have you had any luck there?
Also, Abigail and Nehemiah are apparently buried side by side on the homeplace.
I hope this helps a little. I look forward to hearing from you again.