I had a dilemma. I was running out of space on my Macbook Air. I also had stuff on my old 15″ MacBook Pro that I never moved over because the flash memory on the MBAir was less than that the hard disk on the old machine. and I did a lot of video editing on the old machine that I couldn’t get at unless I powered it up. I bought a small 1 TB disk and moved all my photos, edited movies and music to free up some space on the MBA flash memory. Then I moved all the stuff from the MBP onto the same disk. Now I had a problem. Multiple iPhoto libraries and no way from iPhoto to merge the libraries.
So i had to poke around the net to find some advice because I knew that I’d lose a lot of metadata if I exported the photos and reimported them. I found that all answers on the net seemed to lead to one $30 utility: iPhoto Library Manager. Short Money.
All I have to say is that it took FOREVER, but it worked and I now have a single iPhoto library encompassing several years of my digital photo taking and scans and all the edits and all the slideshows and albums are perfect. And all the metadata and dates were preserved so that the newly merged library has everything in the right place.
I’m sure you are asking “Why didn’t you use migration assistant”. Well, the migration assistant didn’t seem to give me that choice of migrating the old photo library alone. it was trying to move all kinds of stuff. If it was supposed to be able to let me do that, it was not apparent (and I’m pretty used to the various mental models of migrating from machine to machine over the years).
Anyway, if you run into this problem, I recommend iPhoto Library Manager and patience.