Hi Pampoen,
The SA came about because of the name Silva da Shepstone given to my maternal grandmother's first child. In Italian 'da' means 'from' as in Leonardo da Vinci (from the village of Vinci). We couldn't find any relatives with that name in the UK and the only place called Shepstone is in South Africa. At least that was our starting point.
Thank you for the alternative suggestion though as South Africa turned out to be a red herring!!
Maggimot