Synchronise in Premier Pro Background: I've created a multi-cam sequence with three cameras in Adobe Premier Pro CC, which was working fine. I then came to add an additional camera, using CMD + Double Clicking on the Multicam Sequence, it's opened up as a sequence.

Problem: I want to synchronise the new footage against the existing master audio track. So I select both, right click and choose synchronise. However, instead of repositioning the new track, it moves the master audio track. Which obviously offsets the other three cameras.

Beyond recreating the entire MovieCam Sequence, it feels like I'm missing a button somewhere!

Thanks in anticipation!
Use In/Out points.
Put an "In" point on the audio clip, and one on each of the already-synced video clips. Those "In" points should be put on the same sync points (that is, moments that are clearly visible on all clips, say, the clap-board clapping and the sound of the clap!). Whatever sync-point you choose, make sure it's also visible on your non-synced clip. 
Put an "In" point on your non-synced clip, at the sync-point that you've already marked on the synced-clips. 
Choose to sync your sequence by "In" point.
The program will align the "In" points and you should have a synced sequence.