This paper presents a method for modifying the design of the new part for the maximum utilization of existing production lines dedicated to other products. The method takes as inputs a nominal part design and the process information of the (potentially multiple) existing line(s), and produces a modified part design and a process sequence of the new part that maximizes the utilization of available manufacturing processes in the existing lines or equivalently minimizes the addition of new processes dedicated to the new product. The problem is formulated as mixed discrete-continuous multiobjective optimization. A multiobjective genetic algorithm is used to generate Pareto optimal designs for the optimization analysis. A case study on the production of a new machine bracket considering two available production lines is presented.