I have lots of research notes on Sarah Spivey/Spiva (nee Johnson), and you may find that the John Macom you mention is the son of Rev. William Macom and his first wife Cynthia Ann Johnson. Sarah (Johnson) Spivey is the daughter of my 5g grandfather David Johnson who died in March of 1823 in Cape Girardeau County. One of Sarah's brothers was William Johnson who married Jane McGee and Cynthia Ann Johnson was one of their children. Cynthia married Rev. William Macom and their children include George, John, Marion, Levi, Abner, and Mary Ann. After Cynthia died about 1850, Rev. William Macom married second Jemima Thompson.
Consequently, Sarah (Johnson) Spivey/Spiva (the name is spelled both ways by the family) is the great aunt of the children born to William and Cynthia (Johnson) Macom and this certainly explains why she is living in a household that includes Macom children who are probably the grandchildren of her deceased niece. You may find that Thomas Love married a Macom girl to complete the picture of the relationships of the persons in the household in 1870.
Let me know your thoughts and I would appreciate some information on the career of the Rev. William Macom. You can e-mail me directly.