According to Benjamin Shinn in Biographical Memories of Blackford County (The Bowen Publishing Company, 1900, p. 240):
John Ervin was prominent among the early settlers. His early life was spent in Maryland; then he lived in Perry county, Ohio, and came here in 1837. He was married twice, his wives being half sisters.
There were ﬁve children by the ﬁrst wife and eight by the second. The oldest, Naomi, married Hamilton Wheatcraft, and after his death she married Nicholas Friend, the ﬁrst sheriff of Blackford county. They soon went to Iowa; the second, Nancy, married Francis H. Graham, probably the ﬁrst merchant in Hartford City, who came from Belmont county, Ohio. He returned to Ohio and in about 1865 went to Missouri. He was a Methodist preacher, and died in 1875 while he was presiding elder of the Macon City district. Mary, the next child, married Frederick Seelig, at one time county agent and afterwards county commissioner. Samuel was the next, and was one of the county’s best citizens, and Sophia, the youngest of the ﬁrst children, became the wife of Abraham Cassel, the ﬁrst county surveyor.
Elizabeth, the oldest of the last wife’s children, married Rev. William Anderson, a Methodist minister. The other children were: George W., James E., Daniel A., William McK., Jacob E., Benjamin F. and Joshia E. The latter, the only one living, has been for many years a Methodist preacher in the North Indiana conference, and John Ervin himself was a local preacher of considerable ability.
I have been trying to identify John Ervin's wives.
Children of John Ervin and his first wife
John Ervin's first daughter, Naomi, was born in 1812. Samuel Ervin appears in the 1880 census, in which the birthplaces of his parents are listed as Pennsylvania. Sophia (Ervin) Cassell, the last child of John Ervin's first wife, was born in 1816. From this, we know that the first wife was of childbearing age in 1812 and lived into 1816.
Children of John Ervin and his second wife
I know that John Ervin was buried with his [second] wife, Catherine Jane, who died June 30, 1849, in either her 40th or 46th year (the inscription is unclear). According to the 1880 census record for James E. Ervin, his mother's birthplace as Maryland. The death certificate for John and Catherine Jane's last child, Joshua Evan Ervin, lists his parents as John Ervin and Catherine Micky, both birthplaces of Indiana.
I have not been able to find anyone named Catherine Micky. I suspect her maiden name is the same as the full middle name of their son, identified by Shinn as William McK. Based on the dates of births of William's older brother George Washington Ervin and his younger brother Jacob Emory Ervin, I know William's birth was between 1828 and 1840.
Can any of you determine William McK Ervin's full name or the full names of John Ervin's two wives? I have not been able to find John Ervin's will or any relevant information about him not shown here or on his WikiTree page, which I wrote. Further information I have collected on the family is visible in my Ancestry tree (free account required).