Texas Civil Practice and Remedies Code - CIV PRAC & REM § 15.003. Multiple Plaintiffs and Intervening Plaintiffs

(a) In a suit in which there is more than one plaintiff, whether the plaintiffs are included by joinder, by intervention, because the lawsuit was begun by more than one plaintiff, or otherwise, each plaintiff must, independently of every other plaintiff, establish proper venue.  If a plaintiff cannot independently establish proper venue, that plaintiff's part of the suit, including all of that plaintiff's claims and causes of action, must be transferred to a county of proper venue or dismissed, as is appropriate, unless that plaintiff, independently of every other plaintiff, establishes that:

(b) An interlocutory appeal may be taken of a trial court's determination under Subsection (a) that:

(c) An interlocutory appeal permitted by Subsection (b) must be taken to the court of appeals district in which the trial court is located under the procedures established for interlocutory appeals.  The appeal may be taken by a party that is affected by the trial court's determination under Subsection (a). The court of appeals shall:

(d) An interlocutory appeal under Subsection (b) has the effect of staying the commencement of trial in the trial court pending resolution of the appeal.