I moved a copy of the main library onto an external drive
I then created a new library on the same external drive to import a selection of photos from main library
I managed to import some photos once but can't remember what I did
iMac 21.5″, macOS 15.6
The problem with using "Import" to bring in pictures from another Library is that you lose the albums and folders. Most of us who regularly use multiple Libraries use the trusted 3rd party app PowerPhotos ($35) to help out. PowerPhotos will transfer albums and folders intact, and lots more. It uses Photos' own routines, so it doesn't endanger the Photos Libraries' databases. And it offers list views of pictures, metadata editing, and tons of stuff. And they are very helpful when you have questions.
Let us know if you have specific questions that we can help with…
léonie wrote: It is easier to split a large library by duplicating it and deleting from each copy the items you do not want there.
Even the best version of PowerPhotos will not yet preserve the assigned faces and the projects, like slideshows. But duplicating the library will preserve everything. And then you just have to erase in each copy half of the items (in small groups).
This can easily be done with the help of two smart albums. The smart albums will help you to find the photos you want to keep in one library and the photos to delete systematically, so you do not accidentally delete the same items from both copies of the library. Create the smart albums before you duplicate the library, so they will be identical in both copies.
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Excellent!
And here's one that suggests keyword shortcuts, though it's written for choosing favorites:
Choosing Favorites using Keywords in Mac … - Apple Community
It is easier to split a large library by duplicating it and deleting from each copy the items you do not want there.
Even the best version of PowerPhotos will not yet preserve the assigned faces and the projects, like slideshows. But duplicating the library will preserve everything. And then you just have to erase in each copy half of the items (in small groups).
This can easily be done with the help of two smart albums. The smart albums will help you to find the photos you want to keep in one library and the photos to delete systematically, so you do not accidentally delete the same items from both copies of the library. Create the smart albums before you duplicate the library, so they will be identical in both copies.
To partition the items in the two libraries into two separate sets, two smart albums will come in handy. Create these two smart albums with "File > New smart Album".
For example, to create a smart album with all photos older than 5 years, and one album with the photos taking during the last five years:
In a similar way you can partition the set of all photos into "Photo is Favourite" or "Photos is not Favourite" or split them thematically using keywords "Keyword is work" or "Keyword is not work":
I have described it in this user tip: How to Split a Photos Library and Preserve the Albums, Metadata, and Adjustments - Apple Community
and perhaps: Does a large Photos Library make Photos slow? Should we split the library? - Apple Community
Photos -> Help Menu -> Photos Help
Check out the Import Photos and Videos section -> Import from another Photo Library
A great tip, Richard!
breaking up one large Photos library into multiple Photos libraries
