Moving content from one iTunes library to another

Steve,

Audio files resulting from CD rips are not tied to any iTunes account. She can find the ones she wants, add them to her iTunes/Music library on her computer, and then sync her phone the usual way:

Sync your iPhone, iPad, or iPod using your computer - Apple Support

Steve,

OK good, you are on the right track. Do not connect her phone to your computer.

And just to confirm, her phone is currently sync'd to the library on her computer?

Since you mention having ripped those CDs over the years, I assume you can locate the audio files on your computer? Copy them to a flash drive. (Start with one album's worth so you can get your bearings.)

Then copy those files from the flash drive to her computer, and add them to her iTunes/Music library.

Her library on her computer will now have some new songs in it. She can sync her phone to add the new songs onto the phone as well.

If it works for one album, you can do a bunch more. Pls let us know if it succeeds or encounters a problem.

Steve,

Does she have an iTunes/Music library on her computer, which she currently uses to sync her phone? The answer depends on that.