Button to add a song from a playlist into another playlist

Being able to add a song to a playlist from another playlist’s list is a good functional addition when using the app for managing and updating playlists. Sometimes you like to have the song in various playlists, so you know you have it in a playlist but, you have to reproduce it to be able to add it to another playlist from playback menu or even slower, you have to find that song by the search module to add it.