It may be possible to confirm family relationships by comparing test results with Bill 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 67 markers, haplogroup R-M269, FTDNA kit #B13120
It is likely that these autosomal DNA test-takers will share DNA with Bill:
AncestryDNA , GEDmatch T459501[compare], yourDNAportal WIL129d7286, Ancestry member bmadlemII