Are you saying that your ancestor Wesley McGuire married Rachel Fallis and that she is the Rachel McGuire whose household in 1860 included a child of the African-American Strange family in Warren County, Ohio? I don't know who their parents are, or whether they are related to the circuit-riding minister of Ohio, Adjet McGuire. (The spelling of his first name varies.)

I was guessing that Rachel McGuire (or her husband) might be related to Edward McGuire who freed a slave named Reuben Strange in Winchester, Frederick County, Virginia in 1817. It seems that Reuben Strange and/or his son Reuben Strange Jr. moved to Ohio where members of the Strange family were acquainted with Rachel McGuire.

For everything I know about these two families, search Afrigeneas archives for other posts on MCGUIRE and STRANGE families in Virginia and Ohio.