Thanks to [MENTION=40177]anabolism[/MENTION] and [MENTION=648695]Calchas[/MENTION] for clarifying. I'll buy a one way ticket separately, The OW ticket is pretty flexible so if by some chance I miss the connection Im happy to change.

I will be booking it through BA, will I get any success of adding the separate ticketed flight into the same PNR as the OW RTW?