I am placed a family tree for those McGaha's who are descended from the Loudoun County folks. It can be found at WorldConnect: http://wc.rootsweb.ancestry.com/
Type in Jeremiah McGahey to get into the right database (2paschkep).
Also, I am hoping that some male descendants of this line will chose to participate in the DNA study underway at FamilyTreeDNA on the McGaughy and McGaha surnames. Any takers??