dvdbrks

Playing a 3 week competition with 24 pairs using cross imp scoring which is relatively new at our club. A standard Mitchell movement with 9 3 board rounds and an arrow switch for the last 2 (shouldn't this be one?) with seperate scoring each week. One of the pairs has dropped out forcing byes. Is there a standard way of adjusting the score for those pairs that sit out 3 boards? Is it as simple as multiplying their 8 round total by 9/8?