Tex. R. Civ. P. 39

(a) Persons to Be Joined If Feasible. A person who is subject to service of process shall be

joined as a party in the action if

(1) in his absence complete relief cannot be accorded among those already parties, or

(2) he claims an interest relating to the subject of the action and is so situated that the

disposition of the action in his absence may

(i) as a practical matter impair or impede his ability to protect that interest or

(ii) leave any of the persons already parties subject to a substantial risk of

incurring double, multiple, or otherwise inconsistent obligations by reason

of his claimed interest. If he has not been so joined, the court shall order

that he be made a party. If he should join as a plaintiff but refuses to do so,

he may be made a defendant, or, in a proper case, an involuntary plaintiff.

(b) Determination by Court Whenever Joinder Not Feasible. If a person as described in

subdivision (a)(1)-(2) hereof cannot be made a party, the court shall determine whether in

equity and good conscience the action should proceed among the parties before it, or should

be dismissed, the absent person being thus regarded as indispensable. The factors to be

considered by the court include: first, to what extent a judgment rendered in the person's

absence might be prejudicial to him or those already parties; second, the extent to which,

by protective provisions in the judgment, by the shaping of relief, or other measures, the

prejudice can be lessened or avoided; third, whether a judgment rendered in the person's

absence will be adequate; fourth, whether the plaintiff will have an adequate remedy if the

action is dismissed for non-joinder.

(c) Pleading Reasons for Nonjoinder. A pleading asserting a claim for relief shall state the

names, if known to the pleader, of any persons as described in subdivision (a)(1)-(2) hereof

who are not joined, and the reasons why they are not joined.

(d) Exception of Class Actions. This rule is subject to the provisions of Rule 42.