You can add a diagram to the currently opened diagram using File > Add. After you have added the diagram, some blocks and wires may overlap because of this operation; use the mouse and Edit menu commands to reposition them appropriately.
To add block diagrams
1. Open the diagram into which you want to add another diagram.
2. Choose File > Add.
3. In the File Name box, enter or select the name of the diagram you want to add. If you do not see the diagram, select a new drive or directory.
4. Click OK, or press ENTER.
A marquee appears that represents the diagram.
5. Move the marquee to where you want the diagram added and click.