While playing a playlist, click
Library, and then find an item that you want to temporarily
add to the playlist.
Select the item, and then drag it to the Now Playing list in
the List pane.
The item is added to the end of the playlist and
remains in the playlist until you play another item or
playlist.
Notes
You can temporarily add whole albums, artist
lists, and even other playlists to a playlist.
The playlist to which you add items becomes a
temporary playlist until you save it.
You can temporarily add an item from My Computer
or the desktop to a playlist by dragging it to a playlist in the
List pane or by right-clicking the item, and then selecting Add
to Now Playing List.
Notes