Dependent Child Approval.
The child must be "financially dependent" according to a particular and strict definition of that term, and any such claim must be supported by hard evidence. That is often not so easy.
It is surprising how often children who are seen as part of a "family" have, in fact, been adopted either in a documented, western sense of that word or less formally in a customary or cultural adoption. Often children have been brought into a family following a breakdown of an earlier relationship, which will need to be documented. Sometimes there are unexpected difficulties producing birth and identity documentation for children.
The Complex Criteria.
Other possible problems may be to do with identity or how children became separated from parents. These issues can sometimes even lead to a review of the accuracy of claims made in an earlier via application by the parents or by other relatives.
Where children have been placed into the care of people other than their natural parents, questions may arise as to whether those caregivers are temporary or have become "permanent".
New Zealand is a signatory to "The Hague Convention"; an international agreement designed to make it difficult for parents (or others) to cross borders with children while denying others their parental rights. That Convention requires consent from absent parents who may have had no part in the child's life for some years.
While the Dependent Child policy itself seems simple enough, many cases lead to unexpected difficulties in an area that is, by its nature, very sensitive and emotional.