Texas Estates Code - EST § 401.002. Creation in Testate Estate by Agreement

(a) Except as provided in Section 401.001(b), if a decedent's will names an executor but the will does not provide for independent administration as provided in Section 401.001(a), all of the distributees of the decedent may agree on the advisability of having an independent administration and collectively designate in the application for probate of the decedent's will, or in one or more separate documents consenting to the application for probate of the decedent's will, the executor named in the will to serve as independent executor and request that no other action shall be had in the probate court in relation to the settlement of the decedent's estate other than the probating and recording of the decedent's will and the return of an inventory, appraisement, and list of claims of the decedent's estate.  In such case the probate court shall enter an order granting independent administration and appointing the person, firm, or corporation designated by the distributees as independent executor, unless the court finds that it would not be in the best interest of the estate to do so.

(b) Except as provided in Section 401.001(b), in situations where no executor is named in the decedent's will, or in situations where each executor named in the will is deceased or is disqualified to serve as executor or indicates by affidavit filed with the application for administration of the decedent's estate the executor's inability or unwillingness to serve as executor, all of the distributees of the decedent may agree on the advisability of having an independent administration and collectively designate in the application for probate of the decedent's will, or in one or more separate documents consenting to the application for probate of the decedent's will, a qualified person, firm, or corporation to serve as independent administrator and request that no other action shall be had in the probate court in relation to the settlement of the decedent's estate other than the probating and recording of the decedent's will and the return of an inventory, appraisement, and list of claims of the decedent's estate.  In such case the probate court shall enter an order granting independent administration and appointing the person, firm, or corporation designated by the distributees as independent administrator, unless the court finds that it would not be in the best interest of the estate to do so.