Try this:
1. Add to queue, then right-click, choose Play. Check the files in the collection. the .rar should now be sorted to the top. If you start download, small PAR2 will not appear on PAR2 tab. Player will launch after .rar is download.
2. Add to queue, don't do the above, then start download. Small PAR2 will appear on PAR2 tab. After a while, right-click and choose Play. Check files in collection, .rar should now be moved to top, and will download when a thread is next free, so just wait a while and once it's done your player should launch. The PAR2 checking is now suspended until download is complete.
3. If you want .rar to always be sorted to top regardless, check Setup > NZB #2 > Sort rars while importing.
-Hecks