My ggg grandfather Joseph Nelson lived in Corclare, Parish of Shercock, Cty. Cavan. He married Mary Harper (no birthdates )of the Parish of Urney, Cty. Cavan.Their son, John Nelson, was born 1792 near Shercock. These records are shown in the Presbyterian Parish of Coroneary, about 4 miles from Shercock.My info is that Joseph's ancestors came to the area with Cromwell (from England) sometime in the 1600's.Not sure if there is a connection, but it appears your people are near Shercock, as were mine.