Curtain walls frequently contain non-continuous grid lines and mullions. You can merge curtain wall panels to accommodate these design requirements.
Also, merging panels allows you to include a door or other large insert in a curtain wall.

Curtain wall with merged panels
Tips
- You can make linear curtain wall panels with the system panel type only.
- If you join panels of different types, the resulting panel is of the type you first selected.
- Use hidden line view to clearly see which panels are joined. See About Hidden Line Visual Style.