Stammoeder & Progenitor (SM/PROG) Sometimes a woman is both Stammoeder & Progenitor. The oldest/most senior mother of her family to arrive in SA, who is also the partner of a Stamvader (SV/PROG)

Yes indeed. Although she was indigenous to the region, she was the first mother of Meerhofs born here, which makes Krotoa the Stammoeder/Progenitor of the Meerhof family and all their descendants. One didn't have to be an immigrant to be a SM/Prog, only to be the first to procreate in a brand-new bloodline. Therefore, a wife of a new settler was also so labelled irrespective of her own place of birth.

A man is SV/Prog if he is himself an immigrant and has at least one child born here. The bloodline, according to the De Villiers Numbering System, is calculated based on the father, not the mother. If this settler fails to procreate on local soil, then he is not a SV/Prog.

If, for example, a family who already had children immigrated together, the father would be labelled SV/Prog1, and each male child already born before immigration who then has children born here, would be SV/Prog2, SV/Prog3, etc., numbered sequentially according to their own birth sequence from their father. Once again, if no children of their own were born here, it means no SV/Prog title at all.

Quite a lot of children were born to immigrant parents who were not married, and it was totally the norm for slave-women. Nonetheless, they were immigrant-parents of a child born locally, therefore procreating a new family bloodline in these shores.

Your second question, however, is too generic and vague for me to make a call.

Regarding Pieter van Sitten

I found the following -

Sitten - place in Germany - see https://www.antiquemaps.com/maps3/germany/

https://www.antiquemaps.com/maps3/germany/

It is quite possible that Pieter van Sitten was himself an immigrant, but there is just no clear indication on his Geni profile. Therefore, I would personally not award him the SV/Prog title unless some evidence is found that proves it. The Van Sittert family already existed in the Cape at the time with children born here, and it's not clear whether Pieter was perhaps an unlisted child of that family -- it's just speculative (I know), but deserves being viewed as well.

Regarding Pieter van Sitten He was very likely an immigrant - will add a Curator note to that effect

Delia Robertson that sounds like someone, somewhere is going to be offended to think that a baby exits from the actual body of someone with female reproductive parts. I'm all for elimination of gender-based distinctions where the actual sex of the person has no significance, but denying one's physical role in procreating is ridiculous.

See the notes in the about and the discussion - Willem van Wijk

Settlers of the same name would be ranked according to date of arrival.

Pierre le Fèvre is SV/PROG as he was an immigrant and died in South Africa. His sons are not SV/PROGS as there father was the SV/PROG. Daan Botes can help here! Sharon Doubell I don't think Gysbert should be a PROG. if he was the son of Pierre. However. http://www.e-family.co.za/ffy/g14/p14591.htm do not give a father. If he wasn't related to Pierre he would be a PROG. in his own right, - see also Paul le Febvre, Sr who arrived c1694-1696. See https://www.geni.com/projects/Disentangling-the-le-F%C3%A8vre-Huguenot-families-who-came-to-SA/39490