Any guardian, executor of a last will, any trustee by court appointment, and the owners who may be operating leaseholds within the proposed unitized area under the authority of a judgment of a circuit court under an Act of the State of Illinois entitled “An Act in Relation to Oil and Gas Interests in Land”, approved July 1, 1939, when acting under and pursuant to the authority of a court order entered by the court appointing or authorizing such fiduciary or owners to act, or a trustee acting under general authority of appointment by trust document, is hereby authorized and has power to execute plans of unitization, including unit operating agreements, with respect to land or oil and gas rights subject to the control and management of such owners or fiduciary.