Sometimes it's possible to identify a bride with the help of a newspaper report of the wedding, as these can give a description of the dress, bouquet etc. You'd need a list of possible suspects to work from, and then be fortunate enough to find such a report.
In a quick look I didn't spot one for either Isabella Rutherford or who I think may be your grandmother, but you might do better, and, of course, might have more names to look for.