(a) A voluntary acknowledgment as described in Section 301 of this Act and a denial of parentage may be contained in a single document or may be signed in counterparts, and may be filed separately or simultaneously. If the voluntary acknowledgment and denial are both necessary, neither is valid until both are filed.
     (b) A voluntary acknowledgment or a denial may be signed before the birth of the child.
     (c) Subject to subsection (a), an acknowledgment or denial takes effect on the filing of the document with the Department of Healthcare and Family Services, as provided by law.
     (d) A voluntary acknowledgment or denial signed by a minor is valid if it is otherwise in compliance with this Act.