Klaas Johannes Kooystra, born circa 1765 (?), worker.

Klaas was married to
Hiltje Johannes, born circa 1769 (?), died before February 17, 1817, aged at most 48 years.

• 1 : Sybe Klazes Kooystra, born in Grouw circa 1792, barge hand and bargeman.
  Sybe was married in Idaarderadeel on March 17, 1817, at the age of approximately 25 to Antje Uiltjes Veenema (aged 23 years), born in Wartena on January 29, 1794, christened there on February 23, 1794, daughter of Uiltje Hoytes Veenema (peat cutting supervisor) and Feikjen Wybes Feenstra, living in Grouw, died in Lemsterland on August 29, 1863, aged 69 years.