Import photos from one Apple Photos library to another

Yes. Library #1 can import the photos from #2 leaving #2 intact.

However, if you've had a lot of organizational effort done in #2 you would be better off with the paid version of PowerPhotos to import the photos, albums, etc into #1. The difference between letting Photos do the importing and PowerPhotos can be seen in this user tip: Comparison of PowerPhotos vs Photos in Merging One Photos library into Another

Are you using iCloud Photos?

If you are using iCloud Photos with two different Apple accounts, you can use the Shared iCloud Photo Library to share selected photos between both apple accounts. You do not have to share all your photos in the shared library. You can have a personal part and a shared part in each library.

See: How to use iCloud Shared Photo Library on your MacApple SupportOfficial Apple Support › en-us

you won by a nose, OT, Chapeau!

I'm not sure, how AdamBellC is storing the two libraries on the Mac. If the libraries (with two different AppleIDs) are also in different user accounts, the importing should be done on a sneaker drive. To avoid problems with the file ownership we need an external drive with "Ignore ownership on this volume" enabled. A shared folder will not suffice to access a Photos Library from two different user accounts.

Many thanks to both of you for your quick responses. I've delayed replying because you both gave me something to think about!

I have two Apple IDs: 1 = [email protected]; and 2 = [email protected].

Historically I've used ID1 on an iMac that's very old, stuck on Catalina (!) and running on an external SSD after the HDD failed and that's where my main photo library resides; I am currently retiring this device in favour of a brand new MacBook Air.

I use ID2 on my iPhone which has its own photo library, but uses ID1 for Subscriptions.

Previously, to import any photos I take on my iPhone (ID2) into my ID1 library, I have connected my iPhone to my iMac via a cable, but because I need to have the originals on my iPhone, storage is an issue.

So what I'm trying to do is import photos from my ID2 library into my ID1 library in some other way?

Or am I striving for the impossible?

Thanks again for any thoughts ...