She was variously Mena or Philomena in Census but her marriage record says her name was Wilhelmina Geyer. Her tombstone says Philamena and her daughter Josephine named a daughter Philamena. I don’t know which version of her name is correct.

We know William or John William as John’s son from his presence in his father’s household in 1850 and 1860. He is linked to John as his father on find-a-grave. He is designated P5a1f.

John William’s wife was Wilhelmina (or perhaps Philamena) Geyer. They married 7 Oct 1862. I know that from their marriage record from Auglaize County records sent to me by their great-great-granddaughter Barbara Green.

There is a database of Ohio marriages on Ancestry.com based on a transcription of county records, so presumably the same source record. Inexplicably that transcription has 7 Jul 1861.

John William and his wife Philamena are on find-a-grave.

Barbara Green sent me this list of their children:

Josephine Sophia Henrietta Mertz Sheridan:  DOB 11-27-1882  DOD  7-11-1950
Benjamin Frank Mertz: DOB 11-20-1863  DOD         1896
Frederick Oliver:  DOB 9-9-1865    DOD 12-21-1950
Mary Louise Mertz Dixon:  DOB 3-19-1867    DOD 4-2-1941
Charles William Mertz:  DOB 3-8-1869   DOD     1945
Sarah Catherine Mertz Alberding:  DOB 4-6-1871  DOD 7-     -1921
Henry O. Mertz:  DOB 4-8-1872    DOD 1874
George W. Mertz:  DOB 2-5-1874    DOD 1-5-1958
James Albert Mertz: DOB 9-2-1878    DOD 8-17-1966
Emma Rebecca Mertz Wakefield: DOB 4-21-1881    DOD 5-     -1978
Jeanette M. Mertz McCall:  DOB 5-14-1883    DOD       -1961
Harry Mertz:  DOB 4-3-1886    DOD 3-14-1970