Modern engineering systems increasingly rely on the integration of multiple interacting components – each potentially made from distinct materials, manufactured through different processes, or subject to different loading and performance requirements. From aerospace and automotive assemblies to biomedical implants and consumer products, the design of such multi-component systems presents several challenges not typically encountered in single-part designs. These include the need to account for part-to-part interactions, interface behaviour, joint mechanics, manufacturing constraints, and system-level objectives. Additional complexity arises in product family design, where multiple product variants must be developed using shared components and design principles to balance performance, cost, and manufacturability across a range of configurations. This Minisymposium aims to bring together researchers working on computational methods for the design and optimization of multi-component systems. We welcome contributions that explore a wide range of approaches, including: • Topology optimization (density-based, level-set, evolutionary, etc.) • Shape and size optimization for individual parts and assemblies • Gradient-based, heuristic, and ML-based optimization methods • Integration of optimization with CAD, meshing, or automated modelling workflows Both methodological advances and application-driven studies are encouraged, particularly those that provide insight into how optimization tools can be used to design assemblies that are high-performing, lightweight, robust, or easily manufactured. Topics of interest include, but are not limited to: • Topology and shape optimization for assemblies and modular structures • Multi-material and graded-material optimization in multi-part designs • Optimization of joints, interfaces, and connections (mechanical, adhesive, welded, etc.) • Design of systems with detachable or reconfigurable parts • Decomposition-based approaches • Product family design and optimization of shared component platforms • Optimization problems involving contact, interface behaviour, or assembly sequencing • Integration of design for manufacturing and assembly (DfM/A) in optimization • Numerical techniques for handling large-scale or hierarchically structured models • Case studies from industry demonstrating optimization of complex assemblies • Applications involving structural, thermal, fluidic, or multi-physics performance metrics