There should be the options of making "Sealed Notes," meaning handouts or private messages in which the contents cannot be viewed until the one who made it gives permission. (Or the writer gets notified when it's opened.) Once it's 'sealed,' meaning saved, it cannot be altered or deleted by anyone and it's time-stamped. That way a player could do something early on without the GM, or another player(s), knowing. And there's no way they could be making it up on the spot. An example: I'm playing a futuristic tech game and decide to install a 'dead-man switch' to my heart. If it stops beating, an explosive detonates as a last-ditch measure to crush my enemies. I don't want the others to know about it but if I just say I set this up once I die, they might not believe me. So I explain what I did in a Sealed Note and give it to the GM. The GM doesn't know what it says because he can't open it until I say so. When the situation comes up that I die, I click on the note, giving the GM permission to open it. And he sees that I installed this thing three sessions ago. Ka-boom!
