Theunis married Heijltje van Beek on 21 November 1773 in Vreeswijk.86 (Heijltje van Beek was born circa 1750 in De Bilt 86 and died on 30 October 1777 in Vreeswijk 86.)
Theunis also married Maagje Cornelisdr van der Kreeft, daughter of Cornelis Pieters van der Kreeft and Elizabeth Cornelisdr van Kooten, on 19 April 1778 in Vreeswijk 6.,240 (Maagje Cornelisdr van der Kreeft was christened on 4 March 1753 in Houten 95 and died on 21 December 1814 in Vreeswijk 240.)

Spouses/Children:
1. Heijltje van Beek
• Jan Theunisz van Dijk
• Jan Theunisz van Dijk
2. Maagje Cornelisdr van der Kreeft
• Cornelis Theunisz van Dijk+
• Cornelia Theunisdr van Dijk+
• Elisabeth Theunisdr van Dijk
• Elisabeth Theunisdr van Dijk