Per the Steuben County Cemeteries book, Volume 1, pages 967-972, this is the information I could find on your Jackson family, I did not include all the young children.I think her name would be listed on the death records of the children.Philetus died 1921 and William Henry in 1927:
Robert L. Jackson, died June 17, 1880, age 71 years, 11 months, 28 days; Headstone says "Father"--buried L. Gage.
Catherine unknown; "wife of R. L. Jackson" Headstone "Mother", d. Sept. 17, 1879, age 67 years, 3 months, 14 days.Buried L. Gage.
Philetus S. Jackson born 1832-d.1921, m. 1st Harriet L. Hays, m. 2nd Alice V. unknown Does not mention his parents names.
Henry Jackson; note William Henry born 1839-d. 1927, m. Elmina.
Alice V. (unknown) Jackson b. 1856-d.Jan 16, 1920, Mrs Philetus Jackson.
Erma Jackson, died June 30, 1881 daughter of P.S. and A.V. Jackson, age 4 years, 7 months 11 days.
Frank E. Jackson, 1865-1950, m. Arvilla Butz, son of William Henry Jackson and Elmina.
Harriet (Hayes) Jackson, died Nov. 14, 1870, age 29 years, 10 months, 19 days; Mrs. Philetus S. Jackson (!st wife).
Sorry, this is all I could find in burial records for Steuben County, Indiana.