Zoom in to the upstream part of the south branch. Click the Assign Catch Basin button in the Micro-Drainage tab.

The Assign Catch Basin window will pop up.

Drag and draw a rectangular to select the overland node and the nearby catch basin. The selected objects will be highlighted in red. The selected overland node will flash quickly.

Then, click Assign on the Assign Catch Basin window. To see the connection line, navigate to the CatchBasinLine layer under the Support group in the layer table of the map and check on the box to turn on the layer.

Following the same way to assign the catch basins for all the overland nodes including Junctions and Storage Unit. Hold the mouse middle wheel to move the map. For the Catch Basin within the sag area, assign them to the Storage Unit.