Mo. Rev. Stat. § 478.265
The judge of the probate division of the circuit court of any county which has more than four hundred thousand inhabitants may appoint a person to be known as commissioner of the probate division of the circuit court, who shall possess the same qualifications and take and subscribe a like oath as such judge. The compensation of the commissioner shall be limited, determined and paid in the same manner as division clerks as provided by subsection 2 of section 483.243 until June 30, 1981, and section 483.245 after that date except as provided in sections 478.266 and 478.267; provided, however, that said commissioner shall receive a per diem of twenty dollars per day as compensation unless said commissioner is a regular salaried employee serving the probate division of the circuit court in which event he shall receive no per diem allowance; and his service shall extend until terminated by order of the judge of the probate division of the circuit court entered of record but not beyond the term of office of such judge. Subject to approval or rejection by the judge of the probate division, the commissioner shall have all the powers and duties of such judge; but the judge shall by order of record reject or confirm all orders, judgments, and decrees of the commissioner within the time such judge could set aside such orders, judgments, or decrees, had the same been made by him; and if so confirmed such orders, judgments, and decrees shall have the same effect as if made by the judge on the date of such confirmation.
§ 478.265, RSMo
Effective 1/2/1979