Multi-disciplinary Design Analysis and Optimization (MDAO) combines system engineering principles with numerical optimization methods to evaluate and optimize design configurations. However, manufacturing and assembly considerations are often neglected, resulting in theoretically optimal designs that require costly redesigns to ensure producibility. This research integrates assembly requirements for multi-part designs into MDAO workflows, continuing on previous research by the TU Delft which addressed manufacturing considerations for single-part products. The methodology incorporates Joint Assessment Methods (JAM) and Geometry Independent Assembly (GIA) tools within the Design and Engineering Engine (DEE). The DEE is a framework for building MDAO workflows based on design requirements. JAMs assess joint feasibility for specific assembly methods, while GIAs evaluate non-joining constraints such as material incompatibility. A wing rib-skin panel use case demonstrates this approach, with the optimizer selecting an optimal, producible solution. Although effective, the method introduces significant computational overhead, with iteration time ranging from 85 to 205 seconds, depending on the assembly method. Future research may reduce this through early break-off of unfeasible solutions and can include new assembly requirements, to optimize more complex products.