well...now i only able to think of this way....
list all your quest stuff in that npc script..
and show to player when player use the command..
what else do it need ? huh ? just simply list all the quest inside..
and check for the Quest Variable for done , ongoing , unfinish , available quests...
like Gepard said..it is hard way ...but..nvm since you decide using this way..
it would be a godkilling long script then.....