In a method and a system for managing product definition updates for controlling a manufacturing process via a MES system, design information entities each defining manufacturing specifications for a specific product and including sets of data concerning different manufacturing steps are downloaded to the MES system. At the first download, first and second MES information entities are created and stored. The first entities have associated second entities each including data for a manufacturing step and include links to the associated second entities. At each update of a design information entity, a differential package including the whole of the data for a set having undergone changes and for newly added sets, and an identification for unchanged sets, is downloaded. A new version of the second entities corresponding to sets having undergone changes and/or additional second entities corresponding to sets of data that have been added are created and stored.