Okla. Stat. tit. 60, § 60-755: Disposition of interest disclaimed

Unless otherwise provided in the nontestamentary instrument

creating the interest with reference to the possibility of a

disclaimer by the beneficiary, the interest disclaimed shall be

distributed or otherwise be disposed of in the same manner as if the

disclaimant had died immediately preceding the death or other event

which causes him to become finally ascertained as a beneficiary and

his interest to become indefeasibly fixed both in quality and

quantity and, in any case, the disclaimer shall relate for all

purposes to that date, whether filed before or after such death or

other event. However, one disclaiming an interest in a nonresiduary

gift under a trust instrument or otherwise shall not be excluded,

unless his disclaimer so provides, from sharing in a gift of the

residue even though, through lapse, such residue includes the assets

disclaimed. If the disclaimer pertains to a joint tenancy interest

in property, the interest disclaimed shall be distributed or

otherwise be disposed of in the same manner as if the disclaimant

had died immediately preceding the death of the other person having

a joint tenancy interest in the same property whose death most

closely preceded the effective date of the disclaimer or, if no

person having a joint tenancy interest has died, then as if the

disclaimant never owned the joint tenancy interest which was

disclaimed.