Many of the family names in this index are incorrect. These are my grandparents & great grandparents
FUNK should be FONK for all names
Himeter should be Irmiter
I checked the image of the original document. The mistakes were made in the original document, which the FamilySearch index is based on. Since the index must be in accordance with the original record, the spelling cannot be changed now.
You should make a note in your sources. If you ask about this in the Family Tree section of Community you may get some ideas on this issue.
@bearie, there are a couple of ways to get to the Marriage record for Peter Miller and Susan Funk. Probably the easiest way, and the way that will get you to a record that will allow you to edit the names, is to search the Montana County Marriages, 1865 -1950 Collection.
When you search this way, you will get to the index record for the marriage of Peter Miller and Susan Funk: https://www.familysearch.org/ark:/61903/1:1:F343-PQL.
You should find the EDIT is available. Only the names of Peter Miller, his father Matt Miller, and his mother Mary Funk can be edit. It does seem strange that the bride's name, Susan Funk, is not editable.
Unfortunately, that is the limit of what names can be edited. It is true whether you search for Susan Funk or for Peter Miller.
It does appear, in the original document, that some of the instances of "FunK" had an overstrike so that one can see that the name is "Fonk." For others, the name is correctly spelled as "Fonk."
I would suggest going ahead and attaching this source to the records of your family members. Having done that, you can edit the Source and modify the Title so that it shows the correct spelling of the bride. You can also add a note that explains the document errors and that provide the correct spelling. You can do this in the section titled, "Reason to Change Source" or the section titled, "Describe the Record (Notes)." Having thus edited your source, don't forget to click Save.
I am sorry that this is the limit of what can currently be edited in the index record; hopefully, in the future, additional fields will also be editable.