Don't know if you have discovered the Miles Files yet but the following will get you to a lot of information about Isaac Dix and Polly Metcalf: http://www.espl.org/genealogy-research; then scroll down to the Miles Files, then the Main Data Files. I have found it to be more reliable than the Mears Collection. Realize this is more than a year after your original inquiry but I just recently saw it. The 'espl'in the web site address is for the Eastern Shore Public Library.