LieberLieber introduces the new version 1.2 of LemonTree, optimized for collaboration with version management systems. This update provides for improvements in performance and the diffing & merging of model versions. The goal of LieberLieber LemonTree, the revolutionary tool presented in autumn 2016 for the diffing & merging of different model versions, is to leverage the interplay with version management systems. Therefore, for this new release the LieberLieber development team gave special attention to the optimized handling of popular version management systems. In addition to the improved handling of version management, LemonTree now includes automatic model validation.