The Add Area Boundary Line tool was enabled in the model group editor to modify the area boundary.
Click Architecture tabRoom & Area panelArea drop-down (Area Boundary Line) and draw a boundary using the tools in the Draw panel.
Select the area boundary.
Click Architecture tabModel panelModel Group drop-down (Create Group).
In the Create Model Group dialog, name your group, check the Open in Group Editor box, and click OK.
In the Group Editor, click (Add).
Click Architecture tabRoom & Area panelArea drop-down (Area Boundary Line) and draw a boundary using the tools in the Draw panel and use the Line tool in the Draw panel to modify the area boundary.