This question is prompted by the recent question "Which US President are you most closely connected to?"
According to an unverified family tree, my son-in-law is a 2nd cousin 5X removed of Chester Alan Arthur. Unfortunately there is one link that is not present in WikiTree. That of Chester's Gt Grandfather, (Unknown) MacHerg (or Maharg as it appears in our tree, also McHarg on Family Search here). It all hinges on the existance of his son Andrew, brother of Elizabeth https://www.wikitree.com/wiki/MacHerg-1 Chester's Grandmother.
Is there anyone out there who can establish his existance? Born about 1770 in or near Draen, Ballymena, Co Antrim, Ireland? I can't find him in any database.
Going back to my entry for Betty Arthur https://www.wikitree.com/wiki/Arthur-3056 (generated on 26th February 2020), sister of the well doccumented Alan Arthur I note that there was some querery about it's authenticity. At the time I quoted my source as being in good faith from a GEDCOM (sadly containing no citations) generated in Canada in 2007 and passed through the family to me. However the correspondance also contained 3 relevent links to the FamilySearch database and today, 8/11/2020, trying to follow them reveals that they have been removed. So the existance of Betty and probably her husband Andrew are thrown into doubt. I have yet to find out where the Canadians got their data from. If there are any records it would appear that they might be in some parish archive in or near Draen. Otherwise the entries for Betty Arthur and Andrew Maherg are looking unproven.
As an aside, the name Mcherg is Graham spelt backwards, an alledged ruse used by various Border Reiver clans when attempting to evade the forces of Law and Order in the 17th and 18th centuries.