The Board shall consider in making its official findings or decisions only that evidence properly submitted at hearings, with the exception of legal briefs, provided that all parties are given an equal opportunity to submit legal briefs and any responses thereto, but the allowance of the submission of such legal briefs and responses thereto shall be entirely within the discretion of the Board. Information from federal, state or county agencies when submitted on official stationery shall be admitted as evidence only at public hearings, and the Board, in its sole discretion, shall determine the weight to be given to such evidence. Information from the Upper Providence Township Planning Commission or from any other Township agency, board, commission or committee shall be submitted to the Board only at public hearings as authorized by the Board of Supervisors or the Township Manager, but this shall not prevent any member of an official agency, board, commission or committee of Upper Providence Township from appearing and being heard as a private citizen.