My Alexander family lived in southern Ohio, namely Ironton, Lawrence County. I do not have a Joseph Ferguson Alexander in my tree. However, he could be a son of one of my gg-grandfather's siblings.
John Y. Alexander and Elizabeth Ann Hays moved to Mt. Vernon Furnace, Lawrence County, Ohio from Franklin County, Pennsylvania around 1840. Six of the couple's 11 children were born in Pennsylvania. The other five were born in Ohio.
The sons who were born in Ohio were: John Wilson, Joseph and Hiram Alexander. I don't have any other info about Joseph or John Wilson, but I know that Hiram married and had two girls and one boy, Charles. I give you more info if you think that this might be the family that you are looking for.