Okla. Stat. tit. 12, § 12-729.4: Variation of act by agreement of parties

A. The effect of this act may be varied by agreement of the

parties made before or after commencement of an action or

distribution proceeding or the entry of judgment.

B. Parties to a transaction may agree upon the money to be used

in a transaction giving rise to a foreign-money claim and may agree

to use different moneys for different aspects of the transaction.

Stating the price in a foreign money for one aspect of a transaction

does not alone require the use of that money for other aspects of

the transaction.