I realized that I had not fully explained the confusion behind my initial posting.
The problem is that there are multiple Jacob Olingers of the same generation with multiple possible fathers and that I cannot definitively identify which father is the father of my ancestor Jacob M. Olinger (b 24 Dec 1820), husband of Eva Zumbrun.
There are at least three, probably four, and maybe more Jacob Olingers of the same generation in Montgomery County. Marriage records show:
Jacob Olinger - Fanny Cunningham26 Apr 1835 Jacob Olinger - Mary Ann Hale1 Nov 1840 Jacob Olinger - Elizabeth Zumbrun2 Feb 1845 Jacob Olinger - Mary Ann Cunningham5 Mar 1846
Assuming widowers often remarry the sister of first wifes, the husband of Fanny Cunningham may be the same Jacob that married Mary Ann Cunningham.
Also, in the 1840 census, three heads of household have someone old enough to be father and have a young man in the right age range for a Jacob son:
Jacob Olinger (b 1777) of Jefferson Township 1 1 0 1 1 0 0 0 1 0 // 0 0 0 1 1 0 0 0 0 0 [Living alone in 1850 census, age 73. Known to have a son named Jacob]
John Olinger (b. 1776, wife Eva Kaegy) of Madison Township 01 0 2 0 0 0 0 1 0 // 0 0 1 0 0 0 0 1 0 0 [Known to have a son named Jacob]
Confusing matters further, there is a Jacob Olinger (b 1792) born in Montgomery Co who moved to Tuscarawa County, who had a son named Jacob (b Nov 1828) but according to an article published in the the Nov 1982 Laurel Messenger, p 61, Jacob (b 1828) died at the age of 21. There is also a Jacob Olinger (b Nov 1820) from Tuscarawas County, presumably son of another Olinger of the Brethren community there. Several genealogies on the web claim that this is the Jacob that married Elizabeth Zumbrun and moved to Whitley Co, In. However the birthdates and deathdates of the Tuscarawas Jacob do not match those of the Whitley Co Jacob. The Tuscarawas Jacob Olinger (b Nov 1820) moved to Koskiusko County, Indiana (next door to Whitley County, where Jacob (b. 24 Dec 1820) moved.
I found the estate packet for John (b 1776, Eva's husband), which listed Jacob as an heir. I even have a photo of Jacob's signature, but there was nothing that identified John's son as my gggrandfather. If all else fails, I can take the signature to Whitley County and compare it to Jacob's signatures on deeds and mortgages.
In all this confusion, the main evidence I've found for linking John (b 1776) and Eva to Jacob (b Dec 1820) and Elizabeth is geographical proximity (both families being neighbors in the same township). According to Gale Honeyman, a genealogist working at the Church of the Brethren Heritage Center, families almost always married close neighbors.
But, there is a possible contradicting piece of evidence: my Jacob's middle initial is "M" (from his tombstone). Gale Honeyman confirmed that early German families favored the use of mother's maiden name as middle initials of sons, especially when the father's first name is the same as the son. So, John and Eva Kaegy Olinger named their other son John K. Olinger.
Gale agreed with me that geographic proximity probably trumps the middle initial mismatch.
I photocopied nearly everything I could find on Olingers from the Church of the Brethren library and have not finished digesting it, but have not seen anything promising.
So, have you have found something more definitive that ties Jacob (b. Dec 1820) to John (b 1776) and Eva?
If you'd like to take the discussion off-forum, my email address is email@example.com.