This paper introduces a new method to help designers assess the impact of changes to a product platform when introducing a new variant. The method evaluates a platform design by investigating how changing some components will impact other platform design perspectives such as material, function, manufacturing processes and assembly time. To assess the usefulness of this method, it was applied to assess platform changes resulting from successive generations of scanner heads from two manufacturers. The method indicated that one manufacturer improved their scanner head design by improving the functionality of its components and assembly time. Whereas, the other manufacturer's new scanner head used more material and manufacturing processes without benefiting other design perspectives. Compared to existing product family evaluation methods which focus only on maximising commonality between product variants, the proposed method considers potential platform design improvements and assesses them from multiple design perspectives before deciding on reusing existing components or implementing the new design. The information from this method will also complement existing commonality indices.