Import photos from another library in Photos on Mac
If you organise your collections of photos in individual libraries, you can import photos from one library into another.
If the Photos app
on your Mac is open, choose Photos > Quit Photos.To reopen Photos, press and hold the Option key, then click the Photos icon in the Dock.
In the Choose Library dialogue, select the library you want to import photos into, then click Choose Library.
Choose File > Import, navigate to the location of the library you want to import from, select it, then click Review for Import.
Do one of the following:
Import the entire library: Click Import All New Items.
Import selected photos: Select the photos to import, then click Import Selected.
If the two libraries contain duplicate photos, the duplicates appear in the library you imported the photos into.