Split macOS Photos Album

You can cut and paste between albums. So the steps would be:

1. Create new album
2. Goto full album
3. Select all photos you want in new album
4. Select "Cut" from the edit menu (command-x)
5. Goto new album
6. Select paste from the edit menu (command-v)

The selected photos are removed from the original album and added to the new one.

Create new albums as desired and repeat.

You could highlight the photos you want to move, right click them and chose "add to Folder" then pick "New Folder".

Unfortunately, when you go back to the original Album, they are no longer highlighted so you have to select them again to delete them from that Album.

I couldn't find a quicker way.....

I suppose you could create a new album and then cut and paste the photos from your original album into the new album.

-- Rich