I've got several iPhotos libraries (cumulative ~300GB). Started the new Photos app on OS X with a fresh new library with iCloud enabled (yup, gonna have to pay for that). Photos gathered my Photo Stream pictures into it. I opened a couple iPhotos libraries separately (option -> Photos) and converted those, but they remain as separate Photos libraries. File -> Import won't let me select iPhoto nor Photos libraries. Clicking button "Review for Import" (where you'd expect the final Import button would be) complains "Nothing to import / None of these files can be imported into your Photos library". File -> Consolidate is unavailable (gray). If I select one/all pictures, it becomes available (black), but complains "No Referenced Files to Consolidate / The selected items are already stored in the library." If I switch to another Photos library (option -> Photos), same behavior. If I switch to another library (option -> Photos) and then Photos -> Preferences, the iCloud tab says "iCloud features for Photos are only available in the System Photo Library" (that's fine, I'm trying to _move_ these photos _to_ the System Photo Library". The General tab has the "Use as System Photo Library" button, which terrifyingly complains "Switching the System Photo Library will turn off iCloud Photo Library. / Any photos and videos that have not been fully downloaded will be removed from this Mac. Turn on iCloud Photo Library for this new System Photo Library in Preferences." with Cancel / OK buttons. So...how to I get all my photos in disparate libraries (existing precisely because of space reasons under iPhoto) transferred into a single master Photos Library?