Managing and supporting the collaboration between different actors is key in any organizational context, whether of a hierarchical or a networked nature. In the networked context of ecosystems of service providers and other stakeholders, BPM is faced with different challenges than in a conventional hierarchical model, based on up front consolidation and consensus on the process flows used in collaboration. In networked ecosystems of potential business partners, designing collaboration upfront is not feasible. Coalitions are formed situationally, and sometimes even ad-hoc. This paper presents a number of challenges for conventional BPM in such environments, and explores how declarative process management technology could address them, indicating topics for further research.