It may be possible to confirm family relationships by comparing test results with Stephen 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 G, FTDNA kit #84018
Mitochondrial DNA test-takers in the direct maternal line:
Family Tree DNA mtDNA Test Full Sequence, haplogroup H3an, FTDNA kit #676076
It is likely that these autosomal DNA test-takers will share DNA with Stephen: