Okla. Stat. tit. 84 § 133
When any share of the estate of a testator is assigned to a child born after the making of a will, or to a child, or the issue of a child, omitted in a will as hereinbefore mentioned, the same must first be taken from the estate not disposed of by the will, if any; if that is not sufficient, so much as may be necessary must be taken from all the devisees, or legatees, in proportion to the value they may respectively receive under the will, unless the obvious intention of the testator in relation to some specific devise or bequest or other provision in the will, would thereby be defeated; in such case such specific devise, legacy or provision may be exempted from such apportionment, and a different apportionment, consistent with the intention of the testator, may be adopted.
Okla. Stat. tit. 84, § 133