I'm not worried. It isn't that hard to pick up where an interaction was left off, because these games were designed to be taken in on a scene-by-scene basis. One person writes one part of a scene, another person writes another. So in essence, there's always an interruption of scenes by way of time to begin with, depending on how fast the other player replies to another. Simply quoting the last post and posting a reply from there does little, if anything, to hurt the flow. Is it a little odd? Sure, but as long as we understand where the season started and where it's ending, it should be fine. As for two people posting at once, I have the power to move posts from one thread to another, so that's the likely course of action that I'd take.