Tex. R. Civ. P. 37

As amended through August 27, 2024
Rule 37 - Additional Parties

Before a case is called for trial, additional parties necessary or proper parties to the suit, may be brought in, either by the plaintiff or the defendant, upon such terms as the court may prescribe; but not at a time nor in a manner to unreasonably delay the trial of the case.

Tex. R. Civ. P. 37