The information concerning their marriage is from the County of Wellington Marriage Register, Series 16B, page 205.  A copy is on file.  The witnesses at the marriage were Andrew Nodwell and ? McArthur, it is to difficult to make out the second name.

Ontario, Canada Marriages, 1857-1922 Record info about H. Nodwell
Name: H. Nodwell Birth Place: Erin Township Residence: Erin Township Age: 23 Father Name: Andrew Nodwell Mother Name: Bella Nodwell Estimated Birth Year: 1844
Spouse Name: John McMillan Spouse's Age: 26 Spouse Birth Place:Erin Township Spouse Residence: Erin Township Spouse Estimated Birth Year: 1841 Spouse Father Name: Hugh McMillan Spouse Mother Name : Margaret McMillan Marriage Date: 1 Jan 1867 Marriage Place: Hillsburgh Marriage County: Wellington Family History Library Microfilm: 1030067 Source: Indexed by: Genealogical Research Library