Texas Estates Code - EST § 307.002. Joint Executors or Administrators

(a) Except as provided by Subsection (b), if there is more than one executor or administrator of an estate at the same time, the acts of one of the executors or administrators in that capacity are valid as if all the executors or administrators had acted jointly.  If one of the executors or administrators dies, resigns, or is removed, a co-executor or co-administrator of the estate shall proceed with the administration as if the death, resignation, or removal had not occurred.

(b) If there is more than one executor or administrator of an estate at the same time, all of the qualified executors or administrators who are acting in that capacity must join in the conveyance of real estate unless the court, after due hearing, authorizes fewer than all to act.