Any information about Schmidt families who emigrated to South Africa?

Question

My great-grandfather Johan Schmidt, born approximately 1845-55, married Thekla Schwan in South Africa. I am trying to extend our knowledge of the family line.

Comments

Schmidt, a German name, is very common.

Marion Jeanette Schmidt married Wolfgang Koppert in Germany. she from Spanish, he from Polish families originally.

Born after WWII

They are in my tree / jungle