I Am Attempting to Find the Origins of Margaret Glen Who Married James

I am attempting to find the origins of Margaret Glen who married James McClatchey in either Fannett, Franklin Cty, Pennsylvania, or in Derry Twp, Westmoreland Cty, Pennsylvania. She appears to have been associated with a John Glen, the half-brother of Martha Reynolds who married Isaac Donaldson ca. 1765.
The Margaret Glen whom I seek was born in 1755 in the Path Valley, it is said. The term Path Valley can be broadly construed to include not only what is today called Path Valley, but also Tuscarora Valley and Sherman's Valley, so I would be interested in a Margaret Glen from any of those places.
At this time Lack Township in the Tuscarora Valley looks like the most likely possibility, as there were several Glen families living there. However, Margaret also may have connections to Martha Reynolds who lived in Lurgan, Franklin Cty, Pennsylvania, which is located at the entrance to a pass that leads into Path Valley.