If you have libraries from more than one Mac that you’d like to merge together, you will need to first choose which Mac you want to run PowerPhotos on. You’ll need to set up that Mac so that it can access all the libraries you want to merge together. You can do that one of the following ways:
- File sharing across a network. This is the same way you would set up PowerPhotos to directly access a library on another Mac or a network drive. You can find directions for setting this up at Accessing a Photos library on another Mac.
- Copying the library across the network. This starts the same as in option (1), but after you have access to the second Mac’s library, you then use the File > Duplicate Library command in PowerPhotos to make a copy of the library on your Mac’s local drive. This has the advantages that you don’t need to keep the network connection open during the merge process itself, and since everything will be getting copied locally, the merge process will take much less time.
- Putting the library on an external drive. This requires having a Mac formatted external drive with enough free space to hold the library you want to transfer. You would first plug the drive into the second Mac, copy the library from there to the external drive, then plug the drive into the Mac where you’ll be doing the merging.
After making each library accessible from the Mac you’re running PowerPhotos on, you can then choose File > Add Existing Library to add each library to the PowerPhotos library list. Note that since network and external drives are often not indexed by Spotlight, your library might not show up automatically in the list that PowerPhotos presents when you bring up the Add Existing Library window. If you don’t see your library there, click the “Choose Manually” button to choose that library’s location manually.
Once all the libraries are present in the PowerPhotos library list, you can set up a new merge and proceed from there.