The Finite Volume Particle Method (FVPM)is a meshfree generalization of the Finite Volume Method that preserves conservation properties while efficiently handling changing domains through its Arbitrary Lagrangian–Eulerian formulation. Due to its particle-based nature, FVPM is particularly well suited for the simulation of free-surface flows and problems involving large deformations and motion. A tree-based implementation is employed to ensure efficient neighbor search, scalable MPI parallelization, and a uniform particle distribution. FVPM shares a common partition-of-unity framework and data structure with the Partition of Unity Method (PUM), which enables a natural and robust coupling of the two approaches. The PUM is a multiscale method allowing for local refinement and enrichment of approximation spaces, providing high accuracy with comparatively few degrees of freedom and making it attractive for the efficient discretization of complex solid geometries. In this contribution, we present a coupled FVPM–PUM framework for the simulation of fluid–structure interaction problems that includes the treatment of rigid-body motion through a fluid. The approach allows for both translational and rotational motion of immersed solids, arising either from hydrodynamic forces or from prescribed kinematics, and remains applicable in the presence of large displacements. In addition, the framework is designed to support deformation of solids induced by fluid–structure interaction, as well as contact and interaction scenarios facilitated by the adaptive capabilities of FVPM, providing a basis for the simulation of complex FSI configurations.