I have relatives in Indiana that have the last name of Mackey, but my family came from Germany not Ireland. The spelling of their name was changed several times during the time they lived in Indiana. Their name was orginally spelled Macke; then Macca, MacKey, McKey, then finally Mackey. This is do to the census taker during census time.
The family that I have information on is John Henry Mackey m. Anna Maria Angleia Munte in Bartholomew in 1860. They had six children. Most of the Mackey clan live in Seymour, Jackson County, Indiana. The surnames attached to this Mackey line are as follows: Taskey, Klosterman, Kuhlman, Oliger, Emhuff, Mellencamp (Mollencamp, Mollencump, Molloncamp, and Mullencump), and Sager. This is to name a few of the names. My sister and I have been tracing this family since about 1985.