Considering two config.win files namely config1.win and config2.win, place both the files in the Pro/ENGINEER start-in directory. Start a new Pro/ENGINEER session. Select #Tools, #Customize Screen, #File, #Open Settings, and open config1.win by double clicking on it (do not select #Ok). Again select #File, #Open Settings, and open config2.win by double clicking on it. Make sure that "Automatically save to" at the bottom of the "Customize" dialog box is checked, and that the path/filename is set to start-in\config.win. Select #OK. Restart Pro/ENGINEER to load the new merged config.win file automatically from the start-in directory.