Help solve the problem please

Willem Schalksz Van der Merwe married 1643 -1716 married Elsje Cloete born 1649 Germany. They married 9 September 1668. their children are stated below:
1. Sophia VAN DER MERWE, c. 1 Nov 1670, Kaapstad , d. Yes, date unknown
2. Schalk Willemsz VAN DER MERWE, b. 14 Jul 1673, d. Bef 1740
3. Marritje (Maria) Willemsdr VAN DER MERWE, b. 1675, d. 1710
4. Jacoba Jacomina VAN DER MERWE, c. 22 May 1678, d. Yes, date unknown
5. Jacob VAN DER MERWE, c. 11 Feb 1680
6. Petronella VAN DER MERWE, c. 1 Mar 1682, d. Yes, date unknown
7. Aletta VAN DER MERWE, c. 23 Apr 1684, Kaapstad , d. Yes, date unknown
8. Helena VAN DER MERWE, c. 7 Apr 1686, d. Yes, date unknown
9. Pieter VAN DER MERWE, c. 16 May 1688, Kaapstad , d. Yes, date unknown
10. Magdalena Willemsd VAN DER MERWE, b. Abt 1690, d. 1765, Tulbagh
11. Ilya VAN DER MERWE, c. 28 May 1696, Drakenstein , d. Yes, date unknown
12. Elsie VAN DER MERWE, c. 15 Jul 1697, d. Yes, date unknown
13. Hendrik Willem VAN DER MERWE, c. 17 Aug 1698, d. Yes, date unknown
Magdalena Willemsd Van Der Merwe married Pieter Willemz Van Heerden on 17 sep 1708 in Stellenbosch and had a daughter Elsje Van Heerden Pieter van Heerden died in Tulbagh 1763

Maria married Barend Burger (Bernt Burcherdt) after he died she married Lambert Smit.

Thanks Marco

Chris, please see the additional source document that I loaded. The document is titled 'Heijns'. I loaded it as: 'Heyns family tree as drafted by Antonie P. Goossens.' It mentions a date on which she got married to Paul Heyns as 23 September 1684.

The link for this new source document is:
https://geni0-mhcache-com-myheritage.netdna-ssl.com/assets/icn_worl...

Sorry here is the link of the Heyns Family tree as drafted by Antonie Goossens on 21 January 1970:

https://www.geni.com/documents/view?doc_id=6000000041981406233&