How Do I Move My Wife's Photos Into My iCloud Library?

Hi

However you do it, it is going to involve transferring photos from her library into yours.

The simplest way might be to create a second user account on your mac - logged onto your wifes apple ID. You would then have to put the photos library into a folder that can be shared between both accounts, and set the one library as the system library for both accounts. Then when you log into the second account the library will be synced with your wife's iCloud.

The only thing to be aware of - that sync is both ways. All the photos in the library will also be uploaded to your wife's iCloud library and onto her phone.

If you don't want that to happen, then keep the libraries separate on the mac, and periodically export all your wifes photos to a folder (from the photos app in her account), then import those into your photos library.