Mo. Rev. Stat. § 488.633

The circuit judges of the circuit courts of the City of St. Louis and St. Louis County may appoint at least one "friend of the court" in child support matters, pursuant to section 478.422. As compensation for his or her services the friend of the court shall, pursuant to section 478.422, be allowed a fee in each case of not to exceed fifty dollars which shall be taxed as costs.