Recently, non-State organized armed groups with blurring military and non-military wings are&nbsp;increasingly active, bringing legal uncertainty to the law of targeting in non-international armed conflicts&nbsp;(NIACs). This paper aims to specify existing discussions to the child members of these groups. It establishes&nbsp;an analytical framework that centres around Common Article 3(1) as the primary governing rule, where the&nbsp;best interest of the child principle is systematically integrated to assist the understanding of ‘person taking&nbsp;(no) active part in the hostilities’ and ‘humane treatment’ as the two core concepts for the interpretation&nbsp;of the paragraph. The best interest of the child principle provides general guidance of interpretation that&nbsp;special protection shall always be granted to fighter and non-fighter child members. Under the first concept,&nbsp;child members are presumably unlawful targets in case of doubt of their fighter status. Under the second&nbsp;concept, when assessing the effect of an attack, collateral damages to non-fighter child members shall be&nbsp;less tolerated than adult members or ordinary civilians. Admittedly, relevant conclusions are the result of&nbsp;interpretive techniques, and the first sept towards clear legal rules for the issue would be public awareness of&nbsp;the diversified suffers of these child members, including girl members.<br>