Managing change projects in manufacturing enterprises remains difficult and often risky. Some existing research works, good practices and available tools are poorly adapted or hard to autonomously use by industrial decision makers themselves. This article presents and illustrates a change management aided decision approach allowing the construction and evaluation of different possible change projects while taking a given enterprise strategy into account. First, the enterprise is described by using a cross reference to systemic and enterprise modelling approaches. Secondly, the current state of the enterprise is characterized and evaluated from different enterprise performance viewpoints. Thirdly, operational methods are modelled to improve reactivity, flexibility, interoperability and so on, while respecting the behavioural constraints and performance indicator impacts, thus facilitating the building, evaluation and comparison of different change project solutions. Fourthly, this approach is implemented using a methodology and supporting tool.