Now, given that Beth Hawkins's U2c matriline to Catharina goes through her attributed daughter: Adriaantje Gabrielsz, SM
Beth >
Mary Cecilia Thompson Sellars Hawkins >
Mary Cecilia Williams>
Elizabeth Ann Williams>
Anna Cecilia Booysen Williams>
Johanna Catharina Elizabeth van Zyl Booysen>
Catharina Elisabeth Oberholzer>
Geertruy Jacomina Viljoen>
Elizabeth Catharina van der Westhuizen>
Anna Elisabeth van Eck, c4>
Elizabeth Bronkhorst>
Geertruyd Boshouwer, SM>
Arriantjie Gabrielsz Van Cathrijn, SM>
Catharina van Malabar, SM/PROG
I think that a likely scenario is that Adriaantje Gabrielsz, SM is U2c, and the attribution of her as Catharina's daughter is incorrect.
From Arriantjie's About - the attribution appears to come from The First Fifty Years Project's using Mansell Upham's article, 'The Soetkoek Syndrome'
Now Mansell is a fantastic researcher, so first prize would be to get him involved here.
I can't find his article - all I can find is this:
Notes from http://www.ballfamilyrecords.co.uk/robberts/I092.html:
[Adriaantje Gabrielsz] was identified as the voordogter of Catharina, the wife of Cornelis Claasz (Kees de Boer) by Mansell Upham in his excellent article, The Soetkoek Syndrome, based on the evidence of her marriage entry in the Cape Town register. (Mansell Upham, The soetkoek syndrome, in Capensis 2/2001, pages 27-30).
I have assumed that the child with Hendrick Speldenbergh was hers, since Elsie appears later in time in connection with this family (see below). Rather circular reasoning, but there it is!
She also appears as a baptismal witness for her granddaughter Ariaantie, child of her daughter Elsie Speldenbergh, in 1702. The other witness is Robbert Jansen, husband of her half sister Catharina Cornelisse.
In addition, her daughter, Elsie Speldenbergh, appears as a baptismal witness at a number of the baptisms of her cousins, children of Adriaantje Gabriels' half sisters, the children of Kees de Boer and Catharina his wife.
In 1719 an enquiry found her poor and unable to pay her debt of 540 gulden, incurred by her husband Pieter Gerritsz. (source: TANAP: Cape Resolutions, C51, pages 53-56)