A system that includes: a configuration management system configured to receive resource updates submitted by developers of a product line; an update monitor configured, in manual monitoring, to mark each submitted resource update with respective variability data specified as relevant to the update submission, by the developer; and a tracer configured, in automatic monitoring, to trace portions of the updated resource into respective features or products of the product line, to determine variability data relevant to the update submission, wherein when an update request is initiated by the developer, the configuration management system is configured to associate the submitted resource updates with the update request based on common variability data, to provide resource updates on demand, based on variability data, wherein in automatic update, the configuration management system is configured to notify developers on resource updates, based on variability data common to the updated resource and the notified developers.