Okla. Stat. tit. 21 § 1158b
Any person signing a funeral service agreement, cremation authorization form, or any other authorization for disposition shall be deemed to warrant the truthfulness of any facts set forth therein, including the identity of the decedent whose remains are to be buried, cremated, or otherwise disposed of, and the authority of the person to order such disposition. A funeral establishment shall have the right to rely on such funeral service contract or authorization and shall have the authority to carry out the instructions of the person or persons who the funeral director reasonably believes holds the right of disposition. The funeral director shall have no responsibility to contact or to independently investigate the existence of any next of kin or relative of the decedent. If there is more than one person in a class who are equal in priority and the funeral director has no knowledge of any objection by other members of such class, the funeral director shall be entitled to rely on and act according to the instructions of the first person in the class to make funeral and disposition arrangements; provided that no other person in such class provides written notice of objections to the funeral director.
Okla. Stat. tit. 21, § 1158b