Modern software often exists in many different, yet similar versions and/or variants, usually derived from a common code base (e.g., via clone-and-own). In the context of product- line engineering, family-based-analysis has shown very promising potential for improving efficiency in applying quality-assurance techniques to variant-rich software, as compared to a variant- by-variant approach. Unfortunately, these strategies rely on an product-line representation superimposing all program variants in a syntactically well-formed, semantically sound and variant- preserving manner, which is manually hard to obtain in practice. We demonstrate the SiMPOSE methodology for automatically generating superimpositions of N given program versions and/or variants facilitating family-based analysis of variant-rich soft- ware. SiMPOSE is based on a novel N-way model-merging tech- nique operating at the level of control-flow automata (CFA) rep- resentations of C programs, CFAs constitute a unified program abstraction utilized by many recent software-analysis tools. We illustrate different merging strategies supported by SiMPOSE, namely variant-by-variant, N-way merging, incremental 2-way merging, and partition-based N/2-way merging, and demonstrate how SiMPOSE can be used to systematically compare their impact on efficiency and effectiveness of family-based unit-test generation. The SiMPOSE tool, the demonstration of its usage as well as related artifacts and documentation can be found at http://pi.informatik.uni-siegen.de/projects/variance/simpose.