To add a node to a polygonal object

Select the object or group of objects to edit.
Select the Add Node tool ().
Click on any edge of a polygonal object.

Nodes must be added to an edge of a polygonal object. It is possible to enter the new node coordinates, but it will be ignored if the new location is not exactly on an edge. It is better to add the node at an approximate location, then stretch the node to the final position. The exact location can be specfied as coordinates or by snapping with the Stretch tool.