Have you found the proof you need? I haven't "looked at" the message board quite a while!!!
I found the volume mentioned at the Chatham library. There are a few pages that connect the Jefferson's' from Peter Field Jefferson, the first cousin of President Jefferson, down through my Grandmother Rosa Bell. She was Samuel David's (Henry's son) daughter.
I have a paper copy of the actual pages from Vol XVI, #2 and a copy of the volume cover. This may be of interest to you. If so, let me know.