Right-click the root System tile and select Insert > Create General System.
In the LSE grid, the root System tile becomes a frame, and the child System tile is framed by the root system. In the tree, a child system node appears under the root.
Right-click the frame and select Insert > Create General System.
A second child system is created.
Create another child system in the same way.
The system structure comprises a root system and three child systems.