Sending a Soundtrack Project to Final Cut as Multiple Tracks & Preserving Clips?

Hey all-

I have a Final Cut Pro 7 project with multiple tracks of audio that I sent to our sound designer for mixing. He returned them as an OMF file that I now can open in Soundtrack Pro with all the tracks still separated and individually editable. Now we want to make a few minor tweaks to the video and audio back in the Final Cut project. Is there any way to send the project back to Final Cut retaining the multiple, separated audio tracks and clips, the way they appear in my Soundtrack timeline, (so I can edit certain video and audio tracks independently of the others), rather than as a mixed down AAF?

The only way I've found is by exporting as "all tracks", but that's proving itself inconvenient due to creating many redundant and blank portions of tracks, forcing me to constantly render.

Thanks everyone!