Children's agency is inextricably linked to dominant, 'western' conceptualisations of human rights, and remains predominantly representative of northern childhood(s) with wanting imagination about its wider sociopolitical contexts. Despite this, and the growing recognition of its significance, iterations of children's agency centre primarily on children as social actors, often obfuscating its economic, material, democratic or political renderings. Children's social agency, itself, continues to be encumbered by social stratifications and hierarchies, notions of citizenship and politics of governance. The repercussions of bordering agency to suit 'adultist', paternalistic or northern priorities can result in its fetishisation and exclude southern children's agency thus distort knowledge-making. The multiple lives of children in the postcolonies -- beyond innocence, protectionism and individualism -- inform on the diverse ways in which children address, exercise or negotiate their agency. This article, then, seeks to decentre conceptualisations of agency. Thus, it draws on research with the indigenous Hill Sabar communities of Jharkhand, India, framed by postcolonial underpinnings. While the study observed children and young people's (CYP) agency in wide-ranging matters that shaped their sociocultural, material, historical, spatial, structural and discursive realities, here, the focus remains on their familial, social and political agency. Findings reveal how within 'collectivist' communities CYP often enact their agency relationally and reciprocally. They foreground the assemblages of agency that Hill Sabar CYP navigate, adopt and negotiate, intergenerationally, communally and regionally. In response, the article proposes a de-bordering of children's agency to move beyond the siloed, individualist, adultist and northern approaches that constrict it. This, the paper notes, can offer radical sites for interrogation or 'new' insights to attend to its under-theorisation, and perhaps 'free' the concept by 'diversifying' dialogue and research on agency.