There is a book called His House on the Hill, A History of First Ballyeaston Presbyterian Church 1676 - 2004 by Jim Wilson, B.A.
There is a list of members from 1813 in the back of the book, and on page 281 I find two Erskine families listed in succession, of Donomoy:
Robert Erskine 46 Farmer
Jane, wife 36
Elisabeth 13
Thomas 11
John 9
James 7
Sara 5
Robert 1
Thomas Erskine 73 Farmer
Jennet, wife 74
Mary 42
Jennet 40
Thomas Irvin 15 Adopted
I was just in Ballyeaston last week, where I visited the Old Rashee Cemetery near the Four Corners pub, and I remember seeing Erskines there. The Old Rashee Cemetery is very near to, but not part of, the new Rashee Cemetery.
Hope this helps.
DJ