If you will go to rootsweb.com they have a lot of info on James Blackmar clear down to my father.Check it out. No one seems to have a connection. I feel we have a connection to the Blackmore (William) but can't prove it. One day I am going to get on a mission and maybe the help of a genealogist find some tidbit that will lead to the ancestors.
Did you find much into while you were in RI? How about more biographies and personal stuff like wills, probate, etc>There are many possibilities of misspelling the name.Let me know if roots.web helped