(a) A suit provided by this subchapter may be filed only by:
(1) a parent of the child or another person having physical custody or guardianship of the child under a court order; or
(2) the child if the child:
(A) is 18 years of age or older;
(B) does not have a mental disability; and
(C) is determined by the court to be capable of managing the child's financial affairs.
(b) The parent, the child, if the child is 18 years of age or older, or other person may not transfer or assign the cause of action to any person, including a governmental or private entity or agency, except for an assignment made to the Title IV-D agency under Section 231.104 or in the provision of child support enforcement services under Section 159.307.