Okla. Stat. tit. 58, § 709

All issues of fact joined in a probate proceeding must be tried by the court, and in all such proceedings, the party affirming is plaintiff, and the one denying or avoiding is defendant. After the hearing, the court shall give in writing the findings of fact and conclusions of law, and judgments thereon, as well as for costs, may be entered and enforced by execution or otherwise, by the court, as in civil actions. If the issues are not sufficiently made up by the written pleadings on file, the court, on due notice to the opposite party, must settle and frame the issues to be tried, and upon which the court may render judgment.