(1) Rules under section 46 may enable the Board to cause an assessment of a relevant claim referred to in subsection (2) to be made under section 20 on the joint application of the parties to the proceedings concerned and provide, with any necessary modifications, for the application of such provisions of this Act as, in the opinion of the Board, are necessary and expedient in relation to the making of such an assessment and the assessment so made.

(2) The relevant claim mentioned in subsection (1) is one the subject of proceedings brought before the commencement of section 6.