In Griffiths Valuation, there are three possibilities in Ballyhannon for Sarah's father:
McCormack, James: House
McCormick, John: House, offices and land
McCormick, Nicholas: House, office and land
Not Nicholas, as his will, dated 1891, is online and names his children as Robert, Mary, Judith, Margaret, Ann, Eliza and Christina.
William Dickson's WWI Draft Registration card gives her full name as Sarah Margaret Dickson. In 1917, they are living at 25 Knighton Street, South Manchester.