In any county subject to the provisions of Section 31462.1, every retirement allowance, optional death allowances, or annual death allowance, payable to or on account of any member, granted prior to the effective date of Section 31462.1 in such county, shall be recalculated as though Section 31462.1 had been in force in such county on the effective date of such allowance.

Any increased allowances resulting from such recalculation shall be payable only prospectively on and after the operative date of this section in that county.

This section shall not be operative in any county until such

time as the board of supervisors shall, by resolution adopted by a majority vote, make the provisions of this section applicable in such county.