Apple Final Cut Pro 7 - Manual (Page 425)

One way to re-create a merged clip quickly is to edit it into a sequence in the Timeline
and make it independent by Control-clicking it and choosing Make Independent from
the shortcut menu. Then unlink the clip items in the Timeline and make any sync changes.
Relink the clip items and drag them back into the Browser to create a new merged clip.
This method creates a new merged clip, but does not affect any instances of the previously
created merged clip that are already edited into sequences elsewhere in your project.
425 Chapter 29 Merging Clips from Dual System Video and Audio