It may be possible to confirm family relationships by comparing test results with Fred or other carriers of his ancestors' Y-chromosome or mitochondrial DNA.
Y-chromosome DNA test-takers in his direct paternal line on WikiTree:
Family Tree DNA Y-DNA Test 37 markers, haplogroup R-Y5973, FTDNA kit #228693
It is likely that these autosomal DNA test-takers will share some percentage of DNA with Fred:
Family Tree DNA Family Finder, FTDNA kit #228693