We aim at exploring the different approaches to design interactive applications for groups of users using a set of interacting surfaces to perform their tasks with an optimal user experience. Participants are invited to present both the models and/or design methods as well as the case studies and applications they are studying in this context. We would like to set up a discussion group in order to put each person's work in perspective with the notion of territoriality applied to ambient computing and multiple devices. The territoriality theory may serve as a basis for the design of complex interactive applications of quality. From these discussions will emerge a mapping of models and design methods that could be mutualized and combined.