In any case in which an award of benefits creates obligations on the part of an operator or insurer that may be enforced under the provisions of this subpart, such obligations may also be enforced, in the discretion of the Secretary or district director, as follows:
(a) In a case in which the operator is a sole proprietorship or partnership, against any person who owned, or was a partner in, such operator during any period commencing on or after the date on which the miner was last employed by the operator;
(b) In a case in which the operator is a corporation that failed to secure its liability for benefits in accordance with section 423 of the Act and § 726.4, and the operator has not secured its liability for the claim in accordance with § 725.606, against any person who served as the president, secretary, or treasurer of such corporation during any period commencing on or after the date on which the miner was last employed by the operator;
(c) In a case in which the operator is no longer capable of assuming its liability for the payment of benefits (§ 725.494(e)), against any operator which became a successor operator with respect to the liable operator (§ 725.492) after the date on which the claim was filed, beginning with the most recent such successor operator;
(d) In a case in which the operator is no longer capable of assuming its liability for the payment of benefits (§ 725.494(e)), and such operator was a subsidiary of a parent company or a product of a joint venture, or was substantially owned or controlled by another business entity, against such parent entity, any member of such joint venture, or such controlling business entity; or
(e) Against any other person who has assumed or succeeded to the obligations of the operator or insurer by operation of any state or federal law, or by any other means.