The EFH Parties shall cause each other Person that is or becomes a Subsidiary of EFH (other than any such Person or Subsidiary that is “ring fenced,” including the Oncor Entities) to execute a joinder to this Agreement (a) to become an EFH Party (effective as of the date such Person becomes a Subsidiary of EFH or ceases to be “ring fenced”) and (b) to be bound by the obligations of the EFH Parties under this Agreement on a joint and several basis. Reorganized TCEH shall cause each Reorganized TCEH Entity on the date of this Agreement (y) to execute a joinder to this Agreement to become a Reorganized TCEH Entity (effective as of the date of this Agreement) and (z) to be bound by the obligations of the Reorganized TCEH Entities under this Agreement on a joint and several basis.