Hi!
I found this article:
Designate a System Photo Library in Photos
To find where in finder your libraries are I would recommend to go though step 1 - 5 and then click on show in finder instead. A new window should pop up. (The place can be different for each library so best to check all of them.)
When you find the right one you can move to step 6 to make sure you have you big library as the system one.
If you find a library that is empty then you can close the Photos app and delete that library and move on to the next one.
If there are photos in the a library and you are unsure if you have them in you big one then I would recommend to export them to a folder in finder and then do step 1 - 3 to make sure you have selected you big library and then import you photos ether by dragging them from the folder to the photos app or go to File > Import in the Photos app and select the photos from there.
Here are some articles about importing and exporting if you need them:
Import photos from a camera or phone using Photos on Mac
Export photos, videos, and slideshows from Photos on Mac
Short step-by-step summery:
- Find where you libraries are in finder and make sure you have the right one selected as system library.
- Make sure you have all your photos in a safe place / in one library.
- Delete you unwanted libraries.
- Import any photos to your big library if needed.
Hope it helps and good luck!
/Joar
