Transforming Morphs: Smooth & Merge Faces

2.
Use Design > Modify Morph > Smooth & Merge Faces.
3.
The Smooth & Merge Faces dialog box appears.
Smooth boundaries means that the bounding edges of the selected element(s) or sub-elements will also take part in the smoothing:
Preserve boundaries means that the bounding edges of the selected element(s) or sub-elements will stay intact, and only the inner parts are smoothed.
Subdivision level: Use the slider to adjust how much triangulation (subdivision) you wish to achieve. Be aware that a higher subdivision level, used on complex or multiple Morphs, can lead to a high polygon count that can affect model size and ARCHICAD performance.