Okla. Stat. tit. 58, § 58-101: Letters to issue to executor or successor in interest of

corporate executor.

The court admitting a will to probate after the same is proved

and allowed, must issue letters thereon to the persons named therein

as executors, and in the case of a corporate executor, to the

successor in interest of the corporate executor, who are competent

to discharge the trust, who must appear and qualify unless

objections be made as provided in Section 104 of this title.

Provided, a successor in interest shall include a judicially ordered

successor in the event of an assumption by a financial institution

of fiduciary accounts for all trusts in existence on the date of the

assumption, together with those testamentary trusts which come into

existence after the date of assumption.