Okla. Stat. tit. 22 § 329
A member of the grand jury may for ill health of himself or immediate family, or other cause rendering him unable to serve, be discharged before the term is ended or the labor of the grand jury completed; or, if the judge becomes satisfied that any grand juror is willfully refusing to discharge his duty, the court may order his discharge. In the event of the discharge or death of a grand juror, an alternate grand juror shall be appointed to fill the vacancy by the court. The appointment shall be made in the same order in which the alternate grand jurors were selected. If the number of grand jurors and alternates becomes so depleted as to prevent the grand jury from functioning, as many names as the court may order shall be drawn from the jury box in the same manner the original grand jurors and alternates were drawn, and from the names so drawn there shall be summoned as many grand jurors and alternates as can be found and are able to attend as necessary, and if found they shall be summoned in the order in which their names were drawn from the box. If the number be not thus obtained there shall be another drawing in the same manner. When a sufficient number so drawn appears to fill the panel, the grand jury shall in open court be reimpaneled, but subject to challenge and be charged and sworn in the same manner as when the grand jury was originally impaneled.
Okla. Stat. tit. 22, § 329