They had the following children:

• Cornelia (20 Nov 1913, Medan, Indonesia - 28 Jul 1987, Brummen, Netherlands)
• Gerardina Christina "Dies" (24 Aug 1918, Medan, Indonesia - 13 Apr 2002, Waalre, Netherlands)

Notes:

• Religion: Dutch Reformed
• Employment of Gerardina Hendrika: teacher in Rossum
• Witnesses at Roelof Cornelis's birth: Hendrikus Hazelhorst, 34 years old, sergeant-majoor (seargant major), living in Leiden & Jacob Ouwejan, 30 years old, kantoorbediende (clerk), living in Leiden
• Witnesses at Gerardina Hendrika's birth: Jan Heijman, 42 years old, kantoorknecht (clerk?), living in Arnhem & Hendrik van Lill, 38 years old, concierge, living in Arnhem
• Gerardina Hendrika lived in Rossum, Netherlands from Jan 10 1906 until Sep 15 1910
• Gerardina Hendrika took the steamship King Willem III to the East Indies in 1910 . She arrived on Oct 20 1910
• Roelof Cornelis took the steamship de Haan to the East Indies in 1910. He arrived on April 8 1910

Sources:

1. Archief van de ambtenaar van de burgerlijke stand, 1816-1928, Deel: 4751, Periode: 1886, Leiden, archief 0516, inventarisnummer 4751, 1886, Geboorten 1886., aktenummer 1045
2. "Familiebericht". "De Sumatra post". Medan, 26-02-1913. Geraadpleegd op Delpher op 08-08-2016, http://resolver.kb.nl/resolve?urn=ddd:010323625:mpeg21:a0084
3. "Stamboom De Borst", C. Vreugdenhil https://www.genealogieonline.nl/stamboom-de-borst/I2340.php
4. "Netherlands, Gelderland Province Civil Registration, 1800-1952." Database with images. FamilySearch. http://FamilySearch.org : 14 June 2016. Rijksarchief de Gelderland, Arnhem (Gelders Archive, Arnhem).