My great grandfather was their son. He was Lein Baart born Vlissingen 21 February 1868 died Wellington South Africa 21 January 1909. Jacobus Baart was born 20 Aug 1844 in Wijk E, Nummer 81, Vlissingen, Zeeland, Nethelands and died 10 Feb 1873 in Vlissingen, Zeeland, Netherlands. His wife was Jacoba Bostelaar born abt 1849 in Oost-en West Souburg and died 8 February 1922 in East and West Souburg. Lein had a sister Susanna Jacoba born 10 October 1870 in Vlissingen Zeeland Netherlands died 2 March 1872 in Vlissingen, Zeeland, Netherlands.
I have quite a lot of information on the Baart family on my Carlin/Hunt and Schutz/Baart tree.