Audio Sync in Timeline (FCPX)

I am starting the process of editing a feature length film in Final Cut Pro X.

Audio captured separately from the cameras. I have a massive amount of footage and audio.

It was my hope that I would be able to edit the footage in the timeline and then sync the necessary audio with just the clips I used instead of syncing all beforehand.

It appears as though you have to sync the audio with the video in the Event Library only. It then creates a synchronized clip. I have done this successfully. My fear is that I have to sync each clip separately, one at a time (except for multiple camera shots of the same take) before I can begin editing.

So, is the only option to sync audio for all the clips I intend to use (in the Event Library) and then edit and add the Synchronized Clips to the Storyline?

Thanks
Brad