When you finish the CINEMA 4D Exchange design, you can send the information from the Editor window back to ARCHICAD using the File > Send to ARCHICAD command. This returns the model to ARCHICAD and keeps CINEMA 4D Exchange open for the next editing cycle.
If you created new elements in CINEMA 4D Exchange, ARCHICAD will automatically place the new objects at exactly the same location as in CINEMA 4D Exchange.
If you edited selected elements in CINEMA 4D Exchange, the original elements will be replaced with the new geometry.
The material and geometry information of CINEMA 4D Exchange is saved in the retrieved GDL object and will be used the next time you edit the object, but the content of ARCHICAD environment is newly generated during each export.