Section 4
SEC. 4. The grantee herein may, with the approval of the Secretary of Commerce and Communications first had, sell, lease, donate convey or give in usufruct this authority and all property and rights acquired thereunder to any person or corporation: Provided, That for the purpose of such sale, lease, donation, conveyance, or giving in usufruct, it shall be necessary to file in the office of the Secretary of Commerce and Communications an agreement in writing by which the person or corporation in whose favor such sale, lease, donation, conveyance, or giving in usufruct is made, shall bind himself to comply with all the terms and conditions imposed upon the grantee by this authority, and to accept the same subject to all existing terms and conditions.