I would like to see this changed to “and that, where circumstances warrant, payment for more representatives be made at the discretion of the Chair”, because the words “circumstances warrant” imply a little more latitude than the word “exceptional”.
So as a friendly amendment--if you consider it friendly--I would change the words “in exceptional” to...actually, you'd have to remove the words “in exceptional circumstances” and change this to “and that, where circumstances warrant, payment for more representatives be made at the discretion of the Chair”.