I have been researching the Wilkes County, NC Joines family and the Eastern Shore Joynes family. We have started a DNA project that has shown that the two families are related. I haven't been able to find where either Edward or Edmund Joynes (both are in the Northampton records in the 1660s, although the Edward may be a mistake) immigrated to Virginia, unless they were listed as Joyner instead of Joynes. But I haven't found anything linking them to John Joine of 1638.
Is your grandmother's research available anywhere? I think we descend from a Thomas Joyns Jr. who appears in the tithable and tobacco records in the 1720s and 1730s, married a Gertrude Eshon, and moved to Dorchester County, MD around 1733, through his son Ezekiel Joyns of Sussex County, DE, and Wilkes County, NC. Thomas Joyns Jr. was probably the grandson of Edmund Joynes of 1640, the son of either Edmund's son Thomas Joynes Sr. or Edmund's son Major Joynes.