We need to make assumptions in our genealogy research. Many times assumptions are necessary in order to get our work off the ground. But after a point, it may be that the assumption is hindering our work or that we have forgotten that an assumption was made.
If you are guessing that the parents were married near where the first child was born, that is a good start. But somewhere in your notes, indicate why you believe where they were married and that you have no proof. If research does not validate your assumption, it may be that your assumption was incorrect. And if you enter your assumption in your genealogical database as fact, it can be very difficult for that information to go back to being an assumption.
Francis Beiger was born in Warsaw, Hancock County, Illinois, in 1851, the oldest child of her parents. My initial assumption was that her parents were married in Illinois. Turns out that assumption was incorrect. Peter Bieger and Barbara Siefert were married in Cincinnati, Ohio, in 1850, a few months before heading west to Illinois.
My assumption was a good place to begin, but in this case it was a little far afield.