How merge Photos libraries and migrate to a new Mac mini?

My (favorite) cousin (he’s reading this :rofl:) has two Photos libraries on two different Macs. He wants to merge them into a single library on his just-arrived, 1TB Mini and then probably move that library to an external drive. (I’m a Lightroom user so don’t have a clue)

In addition, he is switching the locations of his two Macs and will need to migrate one of them to the new Mini.

Scenario - Old Mini needs to migrate to new Mini. Old Mini will then replace his old MBPro, so he will need to migrate MBPro to Old Mini. Old Mini and Old MBPro each has its own Photos library. Old MBPro will be retired.

He would like to be able to access Desktops and Documents on both Macs from either Mac.

What are the steps he should follow, in order? Just thinking about this makes my head explode.


For merging Photo libraries, use PowerPhotos ($30 purchase for version 2.x). It also performs other helpful Photo library functions.

You can do it without third party tools. If you start with Library A as the system iCloud Photos Library, and let it fully upload. Then change the Library B to the system iCloud Photos Library it will merge A + B.

One of many refs from a very trusted expert on Apple Photos:


Realise my reply was only for iCloud Photos libs which your friends prob aren’t. So probably need Powerphotos. Although you could do it all with iCloud then turn iCloud off.
Once merged, assuming library is managed not referenced, it is very portable. Drag it where you want and double click to open. After that Photos will always open that one until you make a change.