(1) A party to a negotiation for an agreement, or to an agreement, concerning a work group under this subdivision may withdraw from the negotiation or agreement at any time by giving reasonable notice (in writing) to the other parties.
(2) If a party withdraws from an agreement concerning a work group under this subdivision—
(a) the other parties must negotiate a variation to the agreement under section 56; and
(b) the withdrawal does not affect the validity of the agreement between the other parties in the meantime.