In mobile environments, users often need to coordinate their actions with other users with regard to user-individual context information like current location when selecting suitable services for a process. Thereby, some users may prefer to conduct particular services together with certain other users. Such multi-user context-aware service selections could result in complex decision problems – making decision support for the participating users highly valuable or even necessary. To do so, we propose an optimisation-based service selection approach for multi-user context-aware processes. We also show how our approach provides decision support by evaluating its efficacy based on a real-world scenario.