I'm in the process of writing a JSFL command to duplicate a symbol including the nested symbols in it. As far as I've seen many flash designers (and in fact developers too) find this a issue troubling them, when they duplicate a main symbol-forget to duplicate the internal nested symbols and go on and do changes in the internal symbols, only to find out the damage at a later stage.
Hope I would find some takers for this command. I'm already done with a basic construct. Will post it when its complete.