Richtersveld - Potential Transboundary sites (Namibia's Fishriver canyon)
>> the canyon lies in Richtersveld Transfrontier Park
, so geographically they are close. But I think seeing it as an extension is unlikely, as Richtersveld is a cultural site and Fishriver a natural one. Also, Fishriver has been on the tentative list longer. There's also no hint to it in Richtersveld's AB evaluation.