He is married to Sjoerdtje Brouwer.
They got married on December 23, 1926 at Achtkarspelen (Fr), he was 24 years old.Source 3
grandparents
parents
brothers/sisters
children
Johannes Koster | ||||||||||||||||||
1926 | ||||||||||||||||||
Sjoerdtje Brouwer | ||||||||||||||||||
Geboorteregister 1902, Kollumerland c.a.
https://www.graftombe.nl/names/info/179466/koster
Huwelijksregister 1926, Achtkarspelen