(a) A suit under this subchapter may be filed:
(1) regardless of the age of the child; and
(2) as an independent cause of action or joined with any other claim or remedy provided by this code.
(b) If no court has continuing, exclusive jurisdiction of the child, an action under this subchapter may be filed as an original suit affecting the parent-child relationship.
(c) If there is a court of continuing, exclusive jurisdiction, an action under this subchapter may be filed as a suit for modification as provided by Chapter 156.