In a development process, Digital Mock-Up (DMU) is the referential view of the developed product, all along the product states (“as-design”, “as-manufactured”, etc.). In case of long lifetime products, such as boats or planes, each released product has its own DMU. During the use, maintenance operations are made. Some of the modifications are made “on field” and are not always reported to the DMU which is no longer mature. The product lifecycle is impacted and not efficient anymore. This paper focuses on a systematized methodology for checking the maturity level of a DMU by confronting it to the real product it is intended to represent. DMU inconsistencies correspond to unreported product components modifications. The first step of the process is a global comparison between the DMU and a digitization of the in-use product using the Reeb graph. The used comparison criterion is the topology. The second step is to identify the kept DMU components in the digitized dataset and thus deduce inconsistencies. That step implies a new shape descriptor combining topological and functional descriptions of a mechanical part: the Functional Reeb Graph.