I usually have two or three of these tickets open. I need to travel between US and Europe every few weeks and also US/Asia or Europe/Asia 3 or 4 times a year.
I would use the first RTW (example) from Europe to US and Asia, then the second from ASIA to the US, then an award for US/Europe/US and the second RTW for US/Europe/Asia and the remaining part of the first for Asia/Europe etc.....
RTWs are fairly flexible and somewhat easy to change.