20 C.F.R. § 725.364
A representative, appointed and qualified as provided in §§ 725.362 and 725.363 , may make or give on behalf of the party he or she represents, any request or notice relative to any proceeding before an adjudication officer, including formal hearing and review, except that such representative may not execute a claim for benefits, unless he or she is a person designated in § 725.301 as authorized to execute a claim. A representative shall be entitled to present or elicit evidence and make allegations as to facts and law in any proceeding affecting the party represented and to obtain information with respect to the claim of such party to the same extent as such party. Notice given to any party of any administrative action, determination, or decision, or request to any party for the production of evidence shall be sent to the representative of such party and such notice or request shall have the same force and effect as if it had been sent to the party represented.
20 C.F.R. §725.364