Integrate multiple photo libraries

Which system version is installed on your Mac? And are you using iCloud Photos? To get a full merge of two libraries with PowerPhotos, you need at least Power Photos 2.0, and that requires macOS 12 or macOS 13. You will need the full, paid version of Power Photos, but it is worth the investment. On the older system versions the merging with PowerPhotos is limited, but still better than merging by exporting and importing.

You could also merge your libraries with Photos.

• If you are using iCloud Photos anyway, and one of your libraries is already in iCloud, switch temporarily to the second library on the external volume and make it your System Photos Library and your iCloud Photos Library. Then wait until the ilibrary from the external drive has been merged into your iCloud Photos Library. The merged library will sync back to your currently open library. This can take more than a week, if your libraries are large.
• If you have not invested much work into organizing the library on the external volume, you can simply import the photos from the second library into the library on your internal volume. This will not import the albums, only the photos, but the originals stacked with the edited versions as one photo. This import is a new feature in macOS 12 and macOS 13 and great, if we just need to import the missing photos from another library. Photos User Guide for Mac – Apple Support (UK). As far as I can tell, the keywords will not be imported.

You can actually import one library into another, so basically merging them:

Import photos from another library in Photos on Mac - Apple Support

I just ran a number of tests with a 50 photo library with keywords, captions, keywords and locations. I merged it into an empty library using Photos and PowerPhotos. This is what I found was imported by each;

PowerPhotos: Photos:

Albums -----------

Captions Captions

Titles Titles

Original images Original images

Edited images Edited images

--------------- Locations

Favorites Favorites

Can detect and exclude Duplicates

duplicates or not

Neither method included projects.

Both methods could import older iPhoto libraries into a Photos library when the iPhoto library couldn't be migrated into a Photos library.

True but worth noting: only available with the current version of Photos and PowerPhotos offers a more comprehensive merge, not just copying from one to another"

https://www.fatcatsoftware.com/powerphotos/VersionedDocs/v7/merge_libraries.html

When you merge your two photo libraries with iCloud, iCloud will avoid duplicates from different libraries when merging the libraries automatically. But duplicates within the same library will remain.

The most recent version of Photos also includes a tool to scan your library for duplicates. This is only available in Photos 8 on macOS 13 Ventura. Once the mac has been upgraded to Ventura and Photos has finished the scan, you will be seeing a Duplicates album in the sidebar (it will take a while - be prepared to wait for several weeks, if the library is large) The older versions of Photos are only checking for duplicates, when we import new photos, and when creating the curated layout in the Days and in the Memories, but do not show us the duplicates for removal.

I tested again in PowerPhots, to check if the locations will be transferred.

As a test I created a new, empty library. In PowerPhotos I opened the source library and dragged a folder with several albums into the new library.

The test result is a bit confusing. When I am viewing the new library in PowerPhotos, the "Places" column is empty. But when I view the new library in Photos, most of the photos are shown on the Places map, the icons are marked with the location badge. And when I am exporting the photos from Photos, they are tagged with GPS.

The locations are missing for some photos, but checking my iCloud Photos Library where I copied the photos from, I can see, that the locations are missing there as well, so PowerPhotos had nothing to go on.

The most effective way that works with all versions of Photos is with PowerPhotos.

https://www.fatcatsoftware.com/powerphotos/

On which system version did you do the test, OT?

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