On 26 Dec 1667 Cornelius married Magdalena Hendrickse, daughter of Katryntje (-bef 1695), in Southampton, Suffolk County, New York. Born ca 1649 in Flatbush, Kings County, New York. Magdalena died aft 1708.

Magdalena was a witness at the 1708 baptism of her grandson Cornelis, son of Jan and Magdalena (Vonck) Ecker.

Magdalena may have been the daughter of Hendrick and Catrina.

Magdalena was the daughter of the last wife of Jan Teunissen Dam.

Will of Jan Teunissen. Dated 25 Mar 1695. One half of estate to "my deceased wife's daughter's daughter, by name Alida Vonck, the same being located in Midwout adjoining Cornelis Barentse and Mattys Piters and one half to my said deceased wife's daughter Magdalena Vonck and her children (not named). Proceeds from the sale of carpenter's tools to said Magdalena Vonck and all her children, among whom also her daughter Alida Vonck aforesa id is included." Guardians appointed are Justice Joseph Hegeman and Adriaan Ryerse. Wits: Joseph Hegeman, Adriaen Ryersz and Denys Hegeman.