Christina Louisa de Villiers Harris

I believe this is my grandmother. Details we have are sketchy, but we do know she had a sister called Sophy who married into the Devenish family in Johnnesburg. My mother used to talk about her Aunty Sophy and was in touch with the family. We often stayed with Sophy's son Philip and I know he had a brother called Lennox. My grandmother's death certificate lists her as Christina de Villiers Harris. We know she was born in Caledon in the Cape Province of South Africa and we believe there is some connection with Judge John de Villiers also from that area, but we haven't managed to find the link! If anyone can help with further information we would be most grateful!