Children |
 | 1. Willem Koster , b. 23 March 1889, Stadskanaal, Groningen , d. 21 March 1962, Musselkanaal, Onstwedde, Groningen, Nederland (Age 72 years) |
 | 2. Derktje Koster , b. 10 October 1890, Stadskanaal, Groningen , d. Date unknown |
 | 3. Jantje Koster , b. 17 June 1892, Stadskanaal, Groningen , d. 08 May 1929, Stadskanaal, Groningen (Age 36 years) |
 | 4. Arendina Koster , b. 01 August 1893, Stadskanaal, Groningen , d. 27 January 1938, Wildervank, Groningen, Nederland (Age 44 years) |
 | 5. Grietje Koster , b. 23 December 1895, Stadskanaal, Groningen , d. Date unknown |
| 6. Harmke Koster , b. 15 March 1897, Stadskanaal, Groningen , d. 06 July 1897, Stadskanaal, Groningen (Age 0 years) |
 | 7. Arent Koster , b. 06 November 1899, Stadskanaal, Groningen , d. Date unknown |
 | 8. Harm Koster , b. 06 September 1904, Stadskanaal, Groningen , d. Date unknown |
 | 9. Koert Koster , b. 20 February 1909, Stadskanaal, Groningen , d. Date unknown |
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