To edit an existing element in Point mode

Select Insert Element.
Select Point from the Mode option menu.
Specify the portion of the element to be changed by entering two data points.
The former line string is removed and a double rubber band is attached to both points specified. The solid rubber band tells where the new line string will be entered.
Enter data points to define all vertices of the new line string.
Reset to end the line string.
A line is drawn between the last point entered and the point where the dashed rubber band was connected. The modified element is then placed as a complex chain.