Yes, they are at WCC Presbyterian Church Cemetery. Looks like they have a below ground vault with a large flat stone on top. The stone is a tough read, but you can make out enough of the death date and name to know that it is them. There are there together with Doc. William McMachan, Esq. (died 4 Nov 1807), James McMechen (died 9 May 1768), Mary McMechen - wife of James (died 13 April 1754), and David McMechen (his stone has sunk to a point below the death date). If you contact me directly (email@example.com
), I'll send you the pictures that I took.