Have you tried for a copy of the marriage application for info about Fred Kelly and Katherine Roof? Does your grandfather's obituary give any info?Have you tried the 1900 and 1910 Maryland census records for a young Katherine Roof? Have you checked out the Social Security Death Index online for a Katherine Kelly/Richardson? There seems to be a separate NY Roof family and another separate one in PA which must connect back in Germany. Katherine could have been from this PA line.