(1) Without prejudice to its effect apart from this section, this Act so far as it relates to the maintenance of children also has effect as provided by this section.
(2) This Act so far as it relates to the maintenance of children has, because of this section, the effect that it would have if:
(a) each reference to a child were, by express provision, confined to a child of a marriage; and
(b) each reference to the parents of the child were, by express provision, confined to the parties to the marriage;
and has that effect only so far as it makes provision with respect to the rights and duties of the parties to the marriage in relation to the child, including, for example, provision with respect to the rights and duties of the parties in relation to the maintenance of the child.
(3) Nothing in this section affects the operation of the provisions of this Act to the extent that they give effect to an international maintenance arrangement.