Just to clarify, Mary Vanzant's daughter Elizabeth Biggerstaff by Mary's first husband, Benjamin Biggerstaff, did marry Daniel McGaughey. However, Benjamin died in 1782 and Mary twice remarried. To a Mr. Whitecar in 1783 and to John McGaughey in 1786. I don't know what relation John is to Daniel. It is any children of John and Mary that I'm seeking. They may not have had any. I think she was born about 1746, so she would likely still have been of child-bearing age.
Incidently, I'm descended from Mary and Benjamin's son Aaron Biggerstaff. I'm curious on this question because I'm trying to find out more about where Mary was born and who her mother was. Her father was Garrett Vanzant, son of Albertus Vanzant, of New Castle Co., Delaware. Garrett is named in his father's will in 1751 and a Mary is identified as his wife. They both left their marks, so presumably they travelled to or lived in Delaware at the time. However, Garrett and Mary had grown children, including Mary and her brothers Garrett Jr., James, James and Jacob living with them in Tryon County, N.C., by 1768 and may have been in that area for some time. Some think Garrett and Mary married in Delaware or Pennsylvania and most of the children were born there. Others think she was from North Carolina and they only travelled north for the funeral.
So, I'm looking more into the life of their daughter to see if I can get any additional clues.