Digital services, particularly public ones, are often developed within networks comprising multiple organisations with varying capacities. Effective management of such software ecosystems relies on a shared understanding of each party's responsibilities, an aspect not yet fully modelled or understood. Despite widespread recognition, human-centred design (HCD) in digital service development often falls short in this regard. Based on our research and experience, responsibilities for HCD typically lie with the organisation developing the digital service platform. Drawing from empirical data from an ecosystem consisting of libraries, archives, and museums (LAM), we identify the actor role types emerging from the data and examine how the distribution of work among actors influences HCD practices. We recognise the aspects of the platform's user experience (UX) and the UX of the information, and their implications for processes and responsibilities within the LAM ecosystem. We propose the use of HCD processes for orchestration and communication in ecosystems developing digital services. We complement Adner’s “ecosystems as structure” approach by adding discrete HCD actions that enable the materialisation of a value proposition of the ecosystem.