Yes. Once the songs are imported into Hoster the BookID for each is set in stone, so to speak. The BookID is added to the header of each file. So if you move the files or copy the files the BookID goes with it to the new location. Since you are not changing the location of any of her existing files (same drive and folder) then her playlist will be fine.
I do what you are talking about all the time, because we use one computer just for importing then copy them to show computers. Many times rather than trying to pick out which ones to copy I will just copy the whole folder and tell Windows to overwrite all the ones there.
Hope you have a long time to do this....lets see 54,000 + 20,000....my guess is about 6 hours, depending on the drive speed.
