Petronella's full name was Petronella Louisa Carolina Johanna Kamps. She was indeed born in The Hague (Dutch name 's-Gravenhage) on 15 Oct 1881 at 18.00 hrs. She was a Roman Catholic, and her profession was school teacher, later secreteary.
This is the info I could find on her parents and siblings:
Petrus Ludovicus Kamps Born Arnhem 22 Oct 1845, died ’s-Gravenhage 05 jan 1898, aged 52 Son of Johannes Stephanus Kamps and Lucia Carolina Nieren Profession: hotel keeper X Arnhem 27 June 1872 to: Petronella Adriana Monica Timmermans Born Arnhem 04 May 1848, died ‘s-Gravenhage 14 Oct 1915 Daughter of Johannes Franciscus Timmermans and Elisabeth de Rijk
Children: 1. Elisabeth Carolina Reiniera Kamps Born Leeuwarden 29 Apr 1873, died Leeuwarden 02 Sep 1873
2. Elisabeth Carolina Reiniera Maria Kamps Born Leeuwarden 01 June 1874
3. Lucia Carolina Johanna Louisa Kamps Born Leeuwarden 23 Aug 1875
4. Johanna Catharina Francisca Kamps Born Leeuwarden 25 Nov 1876
5. Catharina Arnoldina Pietronella Kamps Born Leeuwarden 16 Aug 1878
6. Petronella Louisa Carolina Johanna Kamps Born ‘s-Gravenhage 15 oct 1881 at 18.00 hrs
7. Maria Wilhelmina Kamps Born ‘s-Gravenhage 20 aug 80
8. Johannes Stephanus Ludovicus Kamps Born ‘s-Gravenhage 04 sep 82
But I must disappoint you; she was not married when she left for St. Gilles. She must have met her husband in Belgium.
I did find some info on a Johannes Antonius (French: Jean Antoine) van Gellicum, also resident of The Hague. He was not a general, though. He was a cavalry captain with the Dutch hussars. In 1924 he was retired and left for Merano. If you like, I can try and find out more about him.