Section 15
SEC. 15. The grantees herein may, with the approval of the Public Utility Commission first had, sell, lease, donate, convey, or give up in usufruct this franchise 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 himselfd to comply with all the terms and conditions imposed upon the grantees by this franchise, and to accept the same subject to all existing terms and conditions.