Dear Fellow Researcher, That is a true Riggs line, emphasis on the "s" at the end. We are a Rigg (no "s") line out of Maryland that added the "s" in the South, along the way. I have collected some stuff on this line. I will try to dig it out but as I have a family member with a health crisis, may not be able to do it soon. Re-remind me sometime at the end of the summer. thanks, Charlotte Rigg Nugent