Best way to merge 3 overlapping Apple Photos libraries and then rebuild my iCloud library?
I'm trying to clean up a somewhat messy Apple Photos setup that developed over the last few years, and I'd like some advice before doing anything destructive.
The easiest way to explain it is chronologically:
Library 1 — oldest / most complete early library
This is my oldest library, covering roughly 2022–2023.
It was mostly left untouched and contains everything from that period.
All originals are stored locally on my Mac.
Library 2 — created from Library 1
At some point I made a copy of Library 1 and continued using that copy.
This second library contains photos/videos from roughly 2022–2024.
Over time, I deleted a lot of the larger videos from 2022-2023 to reduce the size of the library, but otherwise continued adding new photos and videos.
So Library 2 contains newer material that Library 1 doesn't have, while Library 1 still contains some large videos that were later removed from Library 2.
Again, all originals that exist in this library are downloaded locally on my Mac.
Library 3 — current library / iCloud library
Later, I made another copy, this time from Library 2, and continued from there, repeating the process.
This became my current Photos library and is the one currently synced with iCloud Photos.
It contains the newest part of my photo history, but I continued deleting many large videos because I was running low on iCloud storage and wanted to keep most of my historical photos accessible from my iPhone.
This library is set to Download Originals to this Mac, so all of its existing originals are also stored locally.
So the evolution was basically:
Library 1 → Library 2 → Library 3/current iCloud library
Each new library started as a copy of the previous one, but then gained new content and lost some of the larger videos.
What I want to do now
My first goal is to use PowerPhotos to merge all three libraries into a completely new library.
Let's call that:
Master Library
The Master Library would contain the union of everything from all three libraries:
- the older large photos and videos preserved in Library 1
- anything unique to Library 2
- all newer photos/videos from Library 3
I would use duplicate detection during the merge so that overlapping copies don't become unnecessary duplicates.
This Master Library would become my complete local archive and would not be synced with iCloud.
The three old libraries would only be kept temporarily as backups until I've fully verified the merge.
Then I have to decide what to do with iCloud
I want a second, separate Photos library specifically for iCloud.
I'm considering two options.
Option 1: Keep historical photos in iCloud
Create a copy/derived version of the Master Library, remove the largest videos from it, and use that smaller library as my new iCloud Photos library, just like i was doing with every new library copy.
This would let me continue having most of my historical photos available on my iPhone without paying for enough iCloud storage to hold every large video.
My concern is that PowerPhotos documentation says that when an iCloud Photos library is merged into a new library, the iCloud-specific synchronization information is not transferred.
They specifically warn that if you later enable iCloud Photos on the merged library, Photos may not recognize that the local files correspond to photos already in iCloud and may create duplicates.
So I'm unsure whether I could safely connect this new reduced library to my existing iCloud library, or whether I'd first need to completely empty iCloud Photos and upload everything again.
Option 2: Start iCloud Photos from scratch
Keep all historical content only in my local Master Library and Google Photos (i have this too)
Then completely erase my existing iCloud Photos library, create a brand-new empty Photos library, enable iCloud Photos on it, and use iCloud only for new photos/videos going forward.
What I'm trying to figure out
Has anyone dealt with a similar setup?
In particular:
- Does my PowerPhotos merge plan make sense given that all three source libraries have their originals stored locally?
- Is there anything special I should watch out for when merging libraries that are essentially descendants/copies of one another?
- For the reduced historical iCloud option, is there any safe way to reconnect a newly created library to the existing iCloud content without creating duplicates?
- Or would wiping iCloud first and starting fresh be the safer approach?
- Is there a better architecture for keeping one complete local master library and a separate, smaller iCloud-friendly library?
My priority is to make sure I end up with one complete master library containing everything before I delete or change anything in iCloud.