Select the desired part in CAD system.
-> The Select replacement mode dialog is opened.
-> The Open component project? dialog is opened.
Select Open component project or Don't open component project. In both cases the view is switched to PARTS4CAD. In the one case, the project of the component to be replaced is opened, in the other not.
In PARTS4CAD, select the part which should replace the original one. (In this example a longer screw of the same project.)
Click on the button Transfer to CAD (<CAD name>).