You may have already uncovered this, but Frederick Ivey and Prissy Stewart were married in Mecklenburg by bond dated 14 December 1795. This was clearly a second marriage for Frederick Ivey, who had been bound out in 1750 in Brunswick and acquired a family of 6 by the 1782 census. He eveidently moved into Mecklenburg about 1770, where he is listed as white in most tax lists, but as free colored in the 1820 census and in a few tax lists. Frederick died sometime between the 1820 census and the 1821 tax list. Prissy is head of a free colored household, with slaves, in 1830 and 1840 and is listed as black in 1850. (She was age 70 in 1850, perhaps understated since she had married 55 years earlier.) She left a will in 1856, which I haven't seen.

Frederick Ivey, son of Joseph Ivey, seems likely to have been a mulatto or perhaps the son of a freed slave. Prissy may have been black rather than mulatto herself.