Import from another photo library on Mac
If you use multiple libraries, you can import photos from one library into another.
Go to the Photos app
on your Mac.Make sure the library you want to import photos into is currently open.
If it’s not, you need to switch libraries. Choose Photos > Quit Photos. Press and hold the Option key, then click the Photos icon in the Dock. In the Choose Library dialog, 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.
Note: If you participate in an iCloud Shared Photo Library, click the Library pop-up menu in the toolbar and choose the library to import into.
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.