It may be possible to confirm family relationships by comparing test results with Curt 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 H-P96, FTDNA kit #265383
Mitochondrial DNA test-takers in the direct maternal line:
Family Tree DNA mtDNA Test HVR1 and HVR2, haplogroup U5a2b, FTDNA kit #265383
It is likely that these autosomal DNA test-takers will share DNA with Curt: