The contour sketches are managed just as normal sketches are managed in DesignModeler. To modify a meridional contour, you should first select the sketch in the tree view and then click the "Sketching" tab to open the sketch toolbox. If you already have the sketch toolbox open, you can select a different active sketch from the toolbar drop-down list. For models with many different sketches, and for switching between editing one contour or another, this could be tedious. For this reason, it is possible to modify or delete existing edges in a sketch that is not the active sketch as long as it belongs to the same plane as the active sketch. However, newly created edges are added only to the active sketch, so it is imperative that you have the active sketch selected appropriately when creating new edges.