I have a friend with a MBA 128 Gb. She keeps her iTunes library on an external HD (as she should). From time to time she has added music when the ext HD was not connected. That music has been stored on the MBA in the default iTunes Music library. She would like to move that music to the library on her ext HD. Can she simply drag those folders across to her iTunes library on the ext HD or should she use Add or Consolidate? If the uses Add or Cosolidate can she trash the original folders out of the iTunes library on her MBA?