I don't know if you are still looking for your Wilhelmina, but I only knew her name as Minnie:
John Ott (son of John Ott and Catherine) was born 1848 in Michgian, and died 08 Jul 1896 in Toledo Ohio. He married Minnie Knapp on 1884 in Monroe Michigan, daughter of Charles Knapp and Margarett Lehr.
More About John Ott and Minnie Knapp: Marriage: 1884, Monroe Michigan.
Children of John Ott and Minnie Knapp are: Alma Ott, b. 1887, Toledo Ohio, d. date unknown. Julia Ott, b. 1888, Toledo Ohio, d. date unknown. John Carl Ott, b. 1891, Toledo Ohio, d. date unknown. Theodore Robert Ott, b. 18 May 1895, Toledo Ohio, d. date unknown.
The name Knab some how was changed to Knapp, I do have the family back to Germany, Write me direct if you like Carleen_Franklin@Yahoo.com