Tex. Util. Code § 39.457
In the event that the electric utility subject to this subchapter either merges, consolidates, or otherwise becomes affiliated with another owner of electric generation, or completes the jurisdictional separation authorized by Section 39.452(e) and the resulting vertically integrated utility proposes to join a regional transmission organization, and either action adversely affects the rights or obligations of an electric cooperative under a wholesale generation or transmission agreement entered into before the effective date of this subchapter or otherwise adversely affects the electric cooperative's access to its existing generation resources under said agreements, then the utility shall submit a proposal agreeable to the cooperative and the utility for addressing such rights and obligations in the appropriate regulatory proceeding. Such proposal shall be consistent with applicable law regarding the rights and obligations of the electric cooperative and the utility under such existing generation or transmission agreements.
Tex. Util. Code § 39.457