Research in cross-reality systems has studied transitional interfaces that let an immersive system tune the degree of virtual objects from physical reality to virtual reality (VR). Portals have been effective metaphors to enable transitions between the real world, mixed reality (MR), and VR. However, there is a lack of implementations that enable co-located collaboration with immersive systems. This paper describes a cross-reality system for synchronous co-located collaborative tasks. It is instantiated in a performative experience where users perform interactive immersive activities. The novelty relies on the possibility of users sharing the physical space but being perceptually separated in different states of the reality-virtuality continuum. This work aims to advance immersive collaborative design with cross-reality interaction and understand how to design participatory performative experiences that can switch between physical and virtual environments.