If you do not want your daughter's music, then it does not matter where they go...
When you do add songs to iTunes, I prefer to let iTunes keep the music organized (others do not). This way, all your music is centrally located in the 'My Music\iTunes\iTunes Music\Artist\Album\song' directory structure. If you did not do this initially, you can just clear the song references in iTunes and re-Add the music back into iTunes. It will make a copy of the song file and place it in the folder organization I described above.
Make sure you know the difference between song references and song files. iTunes shows you the song references in it's program. These references are just database entries that 'point' to the actual song files stored on your PC. The song files can be anywhere (and everywhere) on the PC. iTunes can play the song file as long as it knows where to access it.
If you delete or move a song file without telling iTunes, you get the dreaded '!'. You can remove the song references from iTunes without deleting the actual song file, or you can delete both using iTunes (as long as the song file is stored in the 'iTunes' folder structure).
Sometimes, you have duplicate song references in iTunes that point to the same song file. Sometimes, you have duplicate references that point to individual (but identical) files. This is why deleting duplicates can be a bit confusing. You need to know what you are dealing with before deleting them.
Also, if you allow iTunes to copy the songs into it's folder organization, it will make a copy of that song, leaving the original file in place wherever it was. You will have two song files on your PC, but only one that iTunes 'sees' and uses. This does not happen when you import songs from CDs, only when iTunes grabs them from other places on your PC.
A bit much in information, but important to have as you are playing with iTunes.
Looks like you are on your way to recovery. Post back if you have additional questions.