Changing iTunes library path - procedural question

Do both of you have Apple Music accounts? Or only your wife? Are you trying to work with two Apple IDs on a single computer? There is a feature called association that may complicate that process. See Authorization vs. association - Apple Community for details. Assuming there aren't any issues there you can use the shift-start-iTunes method to create a new empty library, sign into your wife's Apple ID and enable Sync Library aka iCloud Music Library (which will associate the computer to her ID for a minimum of 90 days) then add the new songs to her library which will match or upload them. Nothing will download automatically.

tt2

As I understand it iTunes Match has the same limitation, in that it requires the computer to be associated with the Apple ID. A computer can only be associated with one Apple ID at a time, and not changed for 90 days after a change. This is going to cause issues if you try to manage both your cloud libraries from a single computer.

tt2

As noted in my user tip:

A mix of up to 10 computers and iOS devices (no more than 5 computers) can be associated with your Apple ID for iTunes Match/Apple Music, automatic downloads, or redownloads of past purchases.

It should be possible to sign in to one Apple ID for iTunes Match. The other user won't be able to use iTunes Match, enable automatic downloads, or redownload any past purchases. Unless I'm mistaken. Given iTunes shows purchases in the cloud that can be streamed or downloaded this last limitation might no longer be there. I'm sure there used to be more clarity in the View and remove your devices that are associated with Apple ID purchases - Apple Support article. I can try testing this behaviour later at home.

As far as I am aware it is the computer that gets associated, so multiple profiles won't help. Creating a virtual machine might be a workaround, but that seems a bit like overkill.

tt2