(1) Work groups may be determined for workers carrying out work for 2 or more persons conducting businesses or undertakings at 1 or more workplaces.(2) The particulars of the work groups are to be determined by negotiation and agreement, in accordance with section 56 , between each of the persons conducting the businesses or undertakings and the workers.(3) The parties to an agreement concerning the determination of a work group or groups may, at any time, negotiate a variation of the agreement.(4) The determination of 1 or more work groups under this Subdivision does not (a) prevent the determination under this Subdivision or Subdivision 2 of any other work group of the workers concerned; or(b) affect any work groups of those workers that have already been determined under this Subdivision or Subdivision 2 .