Unmanned Aerial Systems (UAS) are expected to play a central role in Innovative Air Mobility (IAM), where multiple vehicles and infrastructure elements must be safely coordinated in dense, dynamic low-altitude airspace. Existing formal methods often struggle to capture rich spatial configurations and communication topologies and offer little integration with the physical system. This work proposes a bigraph-based digital twin (DT) framework that unifies formal modeling, verification, and runtime control for multi-UAS operations. Bigraphical Reactive Systems (BRS) with a bi-grid-based spatio-temporal structure can capture UAS–environment relationships and constraints. Preliminary results indicate that our DT framework facilitates adaptive formation coordination through modular IAM operations, dynamic trajectory adjustments, and collision-free navigation in complex environments.