Replacing old iTunes library with newly found music cache

I was holding a friend’s old computer which held two music libraries, one with 4000 items & another with 7000. Due to her mislabeling, we just found her larger one, which I’ve put onto a thumb drive for her & she wants me to walk her through wiping her old iTunes library & putting this larger one on it. All this would be remotely through either e-mail or phone instructions. (We live in different states.) Because of past precedent, I don’t want to mess things up on this & I recommended she get a local computer professional to help her. Is that a better option or am I over-complicating things? She already has the 7000 item thumb drive. What kind of professional should I recommend? Would her local Apple Store be likely to assist her, especially as the end result of this is so she can add the new music to the iTunes on her iPhone?

To be honest, I am not sure that I would want/trust the iTunes store to do it. [I know that back in the day, Apple was very concerned with pirated music and may be annoying, or position themselves as such.]

As you know better than anyone how these libraries are organized, I would just have you do it. But do you want to maintain the strucutre of playlists, etc. or do you just want an import of the files themselves?

Swapping out a library for the new one, I would back up all three libraries (current, new one to be imported, and the the new one that HAS been imported) beforehand… extensively. And there are enough tutorials to do it oneself online.

But personally, I would just select the whole folder and do an important into the current music library. That will copy all of the files and most of the metadata. Your friend will have to reorganize playlists, but this is the best guarantee of success. There is a search for duplicates function in iTunes that works really well and will help with the clean up thereafter.