The Neuberg Formula - Boards with unequal tops

Of course, in the actual example quoted in the introduction, pair 'X' must simply wait until the last table have finished before they can know their real score on the board.

But what happens if the tournament director tells the last table that they cannot play the board because they are too slow? 'Take an average', he says to the last table.

Now we have a real problem. What score to give pair 'X', or indeed all the other pairs who have already played this board?