It may be possible to confirm family relationships by comparing test results with Konrad 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, haplogroup I-L1302, FTDNA kit #N56200
Mitochondrial DNA test-takers in the direct maternal line:
Family Tree DNA mtDNA Test Full Sequence, haplogroup K1a13, FTDNA kit #N56200
It is likely that these autosomal DNA test-takers will share some percentage of DNA with Konrad: