You mention that you have reviewed the records of Niclaus Uhl in Sulzfeld. Do you have any more information on him?
In the book "The HIstory & Genealogy of John Fray," the author, Virginia Fray Lewis, states that the Yowell family history says that John Fray's first wife was a Rebecca Yowell, probably a daughter of Nicholas, who lived nearby, except that no one has ever found a Rebecca Yowell.
John Blankenbaker's research leads to his wife as Rebecca Swindell. However, a close look at the ages of the children of John Fray reveals that there were probably two wives with two families spread apart by about 12-15 years. This leads me back to looking at a Yowell as his first wife. The reason no one has found a Rebecca Yowell is that was the second wife's name taken from later church records and John's will; we don't know Yowell's first name. Consequently, I'm trying to learn more about the Uhl/Yowell families of Culpeper/Madison counties, especially Nicholas.