I am very happy to have come upon this post! I am researching the Mackeys as well. Eliza Mackey (born Eliza Davis) is my great great great grandmother. William David Mackey- my great great great grandfather. The Mackeys and especially the Davises are lines of the family I do not have a lot of information on yet and have recently begun researching. I knew that Eliza's mother was Sarah but had no last name for her & no first name for her husband, Eliza's father. I see that you say these facts are from Ancestry.com and will look into them further. I would like to track down proof that these are the correct parents of Eliza. I do have Sarah living with Eliza and David in 1850.
Their daughter Eliza Mackey Bailey (1856-1938) is my great great grandmother.
I would love to correspond with you further regarding Mackey & Davis information.