Tex. R. Civ. P. 51

As amended through February 20, 2024
Rule 51 - Joinder of Claims and Remedies
(a)Joinder of Claims. The plaintiff in his petition or in a reply setting forth a counterclaim and the defendant in an answer setting forth a counterclaim may join either as independent or as alternate claims as many claims either legal or equitable or both as he may have against an opposing party. There may be a like joinder of claims when there are multiple parties if the requirements of Rules 39, 40, and 43 are satisfied. There may be a like joinder of cross claims or third-party claims if the requirements of Rules 38 and 97, respectively, are satisfied.
(b)Joinder of Remedies. Whenever a claim is one heretofore cognizable only after another claim has been prosecuted to a conclusion, the two claims may be joined in a single action; but the court shall grant relief in that action only in accordance with the relative substantive rights of the parties. This rule shall not be applied in tort cases so as to permit the joinder of a liability or indemnity insurance company, unless such company is by statute or contract directly liable to the person injured or damaged.

Tex. R. Civ. P. 51