38 C.F.R. § 20.504
Rule 504. Extension of time for filing a Substantive Appeal in simultaneously contested claims
An extension of the 30-day period to file a Substantive Appeal in simultaneously contested claims may be granted if good cause is shown. In granting an extension, consideration will be given to the interests of the other parties involved. A request for such an extension must be in writing and must be made prior to expiration of the time limit for filing the Substantive Appeal.