Okla. Stat. tit. 84 § 254
Upon the date set for the hearing of said petition the district court shall hear evidence offered, and shall render judgment according to said evidence, as in other probate cases, and the court shall determine the heirs of the said decedent as of the date of the death of the said decedent. The judgment of the court shall be final and conclusive on all persons appearing or who have been personally served with summons, and shall be final as to all those served by publication, unless any person so served by publication may file in said district court, within twelve months from the rendition of said judgment, a verified petition setting forth that he or she did not have actual notice of the hearing in time to be present at the hearing, and that he or she, in good faith, believes himself to be an heir of the decedent and the facts on which such belief is based, and in that event he shall be heard thereon. The judge of the district court shall, upon the date of filing said petition, set a date for the hearing of such petition and shall cause all parties of record in said cause to be given reasonable notice thereof of not less than ten nor more than thirty days. Upon such hearing the court shall determine the heirship of said decedent and shall render a decision thereon in accord with the facts shown on said hearings; such judgment so rendered shall vacate the original judgment and shall have the same force and effect as in the original hearing thereon, and any party aggrieved may appeal as from the judgment on the original hearing.
Okla. Stat. tit. 84, § 254