I have some information on my family's change from Kauffman, as follows:
My g,g,g,g,g-grandfather, born Hans or John Kauffman in 1751 came from long line of Menonnites (family originated from Switz with Jacob Kauffman, b. 1603 and his g,g, grandson, Henry Kauffman, emmigrated to US via Philadelphia in Sept. 1727).John Kauffman married Mary Ann _____, a Catholic. Apparently, the children were all raised in the Catholic faith.One son, Joseph Kauffman, born in Feb. 1785 used the name "Coffman" instead of Kauffman.This is the first time the spelling appears in my linage and as it remains today and all of Joseph's children had the name Coffman, but all of the children of John and Mary may have used the name also.FYI, John and Mary's children were:Jacob, Barbara, Henry, John, Joseph, Michael, Catherine, and Elizabeth.
Does any of this info match yours?I hope it helps.