Okla. Stat. tit. 84, § 84-171: Disposition to class includes all

A testamentary disposition to a class includes every person

answering the description at the testator's death; but when the

possession is postponed to a future period, it includes also all the

persons coming within the description before the time to which the

possession is postponed. R.L. 1910, Sec. 8401.