Apple - Discussions - iPhoto 4: Consolidate multiple libraries
Update 1/05: I now have a much better discussion of this on my personal digital photography/iPhoto page. This commentary is somewhat obsolete.
This technique works best in my testing so far. Consider two libraries: Main and Secondary.
1. Using iPhoto Library Manager or similar software, open Secondary Library. Adjust albums so all images appears in EXACTLY one album. (Apple has an AppleScript to find images not in any library, see AppleScript site for iPhoto.)
1b. OPTIONAL. In Secondary Library edit roll names to descriptive names.
2. Burn Secondary Library to iPhoto Disc from iPhoto.
3. Switch iPhoto to Main Library. Insert iPhoto Disc.
4. Expand view of iPhoto Disc. Select ALL albums. Drag and drop on Main Library icon.
In testing this preserves:
1. Some roll information. (I have a suspicion it ONLY preserves roll information if you've edited the default names -- based on some other experiments I did on iPhoto 2.
2. The album titles, comments and members.
3. Photo file names, titles, and descriptions.
4. I suspect iPhoto 2 keywords, at least, do NOT make the trip.
I deliberately imported an album from the Secondary Library I knew referenced photos that were in another already imported Secondary Library album. I received a warning about duplicate photos. I said to exclude duplicates from import. 15 photos were not imported, presumably because they'd been previously imported. So this may help.
Until someone writes a smart import/merge, possibly using AppleScript, this may be our best option.