For 'looked-after' and adopted children, physical objects are often the only remaining link to their pasts; a portal to stories of former families, homes, and events. The act of reminiscence, known as 'life story work', can help children to process their pasts and overcome trauma. This paper describes the user-centred redesign of Trove, a digital and physical memory box for storing and curating stories about precious objects. We describe our redesign process, synthesising the insights from previous Trove evaluations with looked-after and adopted children, and three re-design workshops with 4 looked-after children at a therapeutic residential school. Our findings advocate for prioritisation of Trove's digital and physical security, the sustainability of its companionship, and the provision of multimedia storytelling to encourage the construction of identity narratives. Inspired by this, we present and discuss the redeveloped Trove, before analysing our participatory design approach with these complex and under-represented groups.