(a) This subchapter does not affect a parent's:
(1) cause of action for the support of a disabled child under any other law; or
(2) ability to contract for the support of a disabled child.
(b) This subchapter does not affect the substantive or procedural rights or remedies of a person other than a parent, including a governmental or private entity or agency, with respect to the support of a disabled child under any other law.