Guys, thank you so much for your help. I managed to reroute some flights but have to get rid of my desire to go to Moscow on this trip and add 1 more shorter destination in North America instead, e.g. maybe Bahamas.

Since DL78XX (JNB-CPT) does not apply on RTW package, I have to buy a separate round trip ticket from Johannesburg (JNB) to Capetown and it will costs additional 500 USD. Cannot believe it costs this much for a 2 hours flight. Anyone has any better ideas on how I can this Capetown deal included on my trip? I really want to visit both JNB and CPT on this trip but paying additional 500 USD for a 2 hours flight is rediculous. Please help again !