The present invention relates to a method and system for maintaining software products installed on client systems via network. It can advantageously be provided a hierarchy of overlay repositories, for example 'country level' and 'system level'. Country level repositories may contain national language support, code page definitions and other common customizations and add-ons specific for the plurality of clients of a whole country. A dedicated command is issued to a system or to a group of systems. Said command goes through the repository hierarchy—from local to top-level or reversed, local data overwrites central data—and creates a list of files. That list contains per file the location in the repository where it will be taken from during the later download.