Currently Being ModeratedJan 22, 2013 10:50 AM (in response to alex8199)
...can anyone tell me why it is not possible to edit a smart playlist ?
Because the entire content of a Smart Playlist is determined by the rules for that Smart Playlist.
What you can do is change the rules of the Smart Playlist, which will change which songs are added, or not, to the Smart Playlist.
Alternatively, if that doesn't change the list in the way you want, you could set up the Smart Playlist to look at a regular Playlist which has just the songs you want in it.