Currently Being ModeratedJun 28, 2013 5:49 AM (in response to JoAppleG)
Because that's not a feature of either iCloud or iPhoto.
There is no alternative. Any folks who have tried running a Library from the cloud find that it is appallingly slow and there is a very high risk of data corruption as the online servers haven't a clue how to deal with the library.
Use an external disk formatted Mac OS Extended (Journaled)