This paper presents a generic approach for automating the augmentation of product lines using model comparison and variability modeling techniques. Product lines are subject to frequent augmentation to include more products. Our approach aims to reduce manual effort involved in this process by automatically suggesting a tentative augmented product line model, which can serve as a baseline for the final product line. The Common Variability Language (CVL), a generic variability modeling language, is used to specify product lines in this approach. The approach applies CVL Compare, a generic approach for automating the synthesis of a CVL-based product line from a set of existing product models. The approach is illustrated with an example from a train control product line.