I don't know if you are still looking for information on this family. But I just found a marriage record at Immanuel Lutheran Church, Watertown, (rural Amherst), Buffalo County, Nebraska.
Paul GRELLMANN, 22, b. 4 Feb 1862, Germany
Father: E. Grellman Mother: A.A. WOHLEBE
Elisabeth A WUNDERWALD, 16, b 13 July 1868 in Germany
Father: Carl T. Wunderwald Mother: (blank)
Married 39 Oct 1884, Buffalo Co. (northeast of Stanley)
Witnesses: Karl WOHLEBE & Maria WOHLEBE
This is from a translation/transcription of the church
records. BTW, Immanuel Lutheran church is northwest of Stanley, so apparently the wedding was not at the church.
Hope that helps.