Motion/Audio/Final Cut Timeline

Working on a long Motion/Final Cut project for the first time. Started off with a ten minute long screen recording of my narrator recording a keynote presentation. Brought that video into Final Cut and have been sending chunk after chunk into Motion to create the actual graphics, all of which are heavily matched up to the sound.

Now, (of course!) the narrator wants to rerecord almost all of his dialog. In tests, if I place a new audio in the Final Cut timeline (along with the Motion clips), there's no way for me to tell the Motion file to use the updated audio - if I link the Motion clip and new audio in the Timeline, then edit the Motion clip in Motion, it still references the original audio. Is there a simple way I can tell Motion to use the updated audio instead, or (what I fear is the case) am I stuck with having to manually dump each edit audio clip directly back into the individual motion file? Because my video is heavily audio-timed, I need to have the audio in the Motion file.

Thanks!