Here's the story: my hard drive crashed in my macbook. I replaced the hard drive but still had my old , large (40-50 gb) iPhoto pictures on the old hard drive. I began using "Photos" on the new hard drive and had imported photos from iPhoto from what I had on my phone. This created my "System Photo Library". I was just able to recover my old photos from the old broken hard drive using Data Rescue. I imported my recovered old photos in to Photos and now have my "Photos Library 2". I have not used iCloud photos yet but wanted to due to the hard drive failure that almost lost all my photos. But now I understand that you can't merge 2 libraries or have 2 in iCloud. There has to be some kind of work around for this. I never intended to have 2 different libraries, it was only due to a hard drive failure. I want one library with all my photos and the ability to have them all in iCloud. Is there anyway to combine all my pictures and just create a new "System Photo Library"? Can anyone shed some light on this and offer some help?