Okla. Stat. tit. 58, § 289

Whenever property not mentioned in an inventory that is made and filed, comes to the possession or knowledge of an executor or administrator, he must cause the same to be appraised in the manner prescribed in this article, and an inventory thereof to be returned within two (2) months after the discovery; and the making of such inventory may be enforced, after notice, by attachment or removal from office.