According to Harness Heroines I book by Helen Harkness Ryan:
    Robert Harkness born County Tyrone, Ulster, Northern Ireland (no date) Came to America n 1774 with son William, landed Philadelphia, migrated south and fought in Revolutionary War for State of N. Carolina, received grant of 300 acres, in lieu of pay, in S. Carolina, on Buffoloe Creek.
1790 census had 7 children:
1. Agnes, b. 1762, in Ireland, Married, Oct. 1782, Archibald Neill in Abbeville, S. Carolina later moved to Green Co., Alabama.
2. Jane Harkness, b. 1766, Ireland, married, 1785, James Pettigrew at Robert's residence Hopwell Church, Rev. Robert Macklen, Presbyterian, Witnesses Patrick Norris John Till or John Varnum, Bridesmaid, Isabella Lindsay.  James traveled to Tuscaloosa, Alabama in 1841, drew his pension and died there in 1854.
3. Robert Harkness, b. 1769, Ireland
4. William Harkness b. 1769, Ireland, died 1855, Green Co., Alabama, Married Sept. 20, 1792 Ann Reed Baskin, in Abbeville. move to Green Co., Alabama.
5. John Harkness, B. 1774 County Tyrone, Ireland, D. 1854 Anderson Co., S.C. married before 1804, Nancy Norris (b. 1782) daughter of John Norris and Mary Browne.  John's will was probated April 1854 at Anderson Co. the executors were his 3 sons.
6.  James Washington Harkness, b. July 1780, Abbeville Co. S. C. D. July 9, 1851 Butts Co., GA., married Rosanna Baskin, Abbeville.
7. Andrew Harkness, b. after 1780, in S. Carolina no further info.