If any person entitled to a benefit of not more than five hundred dollars ($500) from this system is a minor who has no guardian of his estate, the board may pay it to the person entitled to the custody of the minor to hold for the minor, if the person files with the board his acknowledged and verified statement that the total estate of the minor does not exceed one thousand dollars ($1,000) in value. Payment so made is a full discharge of the board and this system. The person shall account to the minor for the money when the minor reaches the age of majority.