(1) Where the basis of calculation of retirement benefit provided by a pension scheme is altered from a defined contribution basis to a defined benefit basis after the date of the decree the designated benefit payable from that pension scheme shall be calculated on a defined contribution basis in accordance with the relevant regulations of this Part.
(2) Where the basis of calculation of retirement benefit provided by a pension scheme is altered from a defined contribution basis to a defined benefit basis prior to the date of the decree the designated benefit payable from that pension scheme shall be calculated in accordance with the following:
(a) where the member spouse's retirement benefit in respect of a period of retirement benefit service is calculated on a defined contribution basis, while his retirement benefit in respect of a subsequent period is calculated on a defined benefit basis, the designated benefit in respect of the defined contribution part and the designated benefit
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