Have you created a profile for yourself here on WikiTree, and added the family connections that you do know about? That would generally be the first, best step towards making connections with the Powells in South Africa.
The name Baden Powell is very familiar to me, Robert Baden Powell fought in the Boer Wars in South Africa. He eventually returned to Britain and formed the Scouting movement there, leading to Boy Scout organizations all over the world. I wonder if your Grandfather is related. It seems likely!