Mo. Rev. Stat. § 86.360
The board of trustees provided for by section 86.213 is hereby authorized to consolidate, combine and transfer funds provided by sections 86.010 to 86.193 with the funds provided by sections 86.200 to 86.366 in such a manner as will simplify the operations of the two systems. Separate records shall be maintained only to the extent necessary to determine and pay the benefits provided by sections 86.010 to 86.193 for those policemen electing not to become members of the retirement system provided by sections 86.200 to 86.366. The board of trustees may accept the membership records of the older system in lieu of the requirements in section 86.210. The board of trustees may authorize the use of the same actuarial assumptions and interest rate in the calculation of the contributions by the cities for both systems and the accrued liability rate may be a combined rate for both systems.
§ 86.360, RSMo