Okla. Stat. tit. 58, § 555

All matters, including allowed claims not passed upon on the settlement of any former account, or on rendering an exhibit, or on making a decree of sale, may be contested by the heirs for cause shown. The hearing and allegations of the respective parties may be postponed from time to time, when necessary, and the court may appoint one or more referees to examine the account and make report thereon, subject to confirmation; and may allow a reasonable compensation to the referees, to be paid out of the estate of the decedent.