child of the marriage

"child of the marriage" means a child of both parties to the marriage in question or a child of one party to the marriage accepted as one of the family by the other party; and "child" in this context includes an illegitimate child of, and a child adopted by, either of the parties to the marriage in pursuance of an adoption order made under any written law relating to adoption;
ACT 164 - LAW REFORM (MARRIAGE AND DIVORCE) Act 1976
2. Interpretation.