38 USC 7105A - Simultaneously contested claims

(a) In simultaneously contested claims where one is allowed and one rejected, the time allowed for the filing of a notice of disagreement shall be sixty days from the date notice of the adverse action is mailed. In such cases the agency of original jurisdiction shall promptly notify all parties in interest at the last known address of the action taken, expressly inviting attention to the fact that notice of disagreement will not be entertained unless filed within the sixty-day period prescribed by this subsection.
(b) Upon the filing of a notice of disagreement, all parties in interest will be furnished with a statement of the case in the same manner as is prescribed in section 7105. The party in interest who filed a notice of disagreement will be allowed thirty days from the date of mailing of such statement of the case in which to file a formal appeal. Extension of time may be granted for good cause shown but with consideration to the interests of the other parties involved. The substance of the appeal will be communicated to the other party or parties in interest and a period of thirty days will be allowed for filing a brief or argument in answer thereto. Such notice shall be forwarded to the last known address of record of the parties concerned, and such action shall constitute sufficient evidence of notice.