I am struggling to do something similar that you have mentioned with Graphiti 0.9.1.
Just few questions around your example:
1. Which version of Graphiti you are using.For me addIfPossible()method is giving some errors with version 0.9.1.This worked in version 0.8.2.
2. I suppose "FbsFactory" is your own class and the diagramBO object that you are passing the set of BuisnessObjects.
Correct me if wrong.