(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 in respect of the defined benefit part shall be calculated separately in accordance with the relevant regulations of this Part;