(a) The court may order either or both parents to provide for the support of a child for an indefinite period and may determine the rights and duties of the parents if the court finds that:
(1) the child, whether institutionalized or not, requires substantial care and personal supervision because of a mental or physical disability and will not be capable of self-support; and
(2) the disability exists, or the cause of the disability is known to exist, on or before the 18th birthday of the child.
(b) A court that orders support under this section shall designate a parent of the child or another person having physical custody or guardianship of the child under a court order to receive the support for the child. The court may designate a child who is 18 years of age or older to receive the support directly.

(c) Notwithstanding Subsection (b), a court that orders support under this section for an adult child with a disability may designate a special needs trust and provide that the support may be paid directly to the trust for the benefit of the adult child. The court shall order that support payable to a special needs trust under this subsection be paid directly to the trust and may not order the support be paid to the state disbursement unit. This subsection does not apply in a Title IV-D case.