Interesting thread.
More and more little scenarios being added but could I just suggest that if a ruck had formed, then all players in the ruck end up off their feet with the ball in there somewhere, not having been won by either team. Before another player acting as the SH can go ferreting in there trying to dig the ball out, I would whistle and stop play calling unplayable (ie: unsuccessful end to a maul) and award a scrum to the team going forward or as per the other order of scrum feed as per Law 16. I wouldn't be standing there trying to work out where the offside lines were hoping that someone is eventually going to get the ball to their side and then keep playing.