Hi there.
I am not sure of the regulations nowadays but back in the 80's you could get one estuary added to your license. I had Amatikulu on mine and netted mullet there.
I remember another fisherman from Mtunzini that had the Umlalazi on his license. We only netted near the mouth so I do not know where the authorities would consider the mouth to end and the estuary to start. You could possibly check with Ezimvelo for possible clarity on that score and while at it, if an estuary can still be added to a license. Good luck and happy casting.