Many families did move together. David and Hannah McKee were in Fleming and Mason County; KY, Brown Co, IN; Hendricks Co, IN (1834-50); Jefferson Co, IA (1855); Hamilton Co, IA (1860-ca1875); Hendricks Co, IN (1876-1877 he died 2 Oct). Hannah had died Jul 1862 or 63 in Homer,IA.
You may want to check Hendricks Co, IN probate records for a will and list of heirs.
Lydia McKee Doane was a daughter.
J.O.McKee, Jr. did not list any MaryAnn in his research that I have nor did I find her in his Fleming Co, KY and surrounding counties marriage index that I have. He may not have known about her. Try to follow David and the Eatons in those counties, especially 1850 Federal and some state census.