When the heat winners go through to the next round, it might be nice/sensible/fair if they don't have to compete with those they've already competed with. I.e. if winner of group 1 goes into the first 2nd round group, and the 2nd place goes into the 2nd 2nd, and the 3rd into the 3rd, and then the winner of group 2 goes into the second 2nd round group, and so on, (striped, if you like) then each story will compete against new opposition. Just an idea!