Hi Pete,
That's intentional. Fragments are for storing and reusing parts of a model, not for concurrent collaboration. When dividing work by package and then merging the whole, duplicate packages should be deleted beforehand. Please note that a fragment is a closed set of model elements as mentioned in the previous thread.
We know that concurrent collaboration is not easy in StarUML. Because model elements referencing each other in a complex way, effective collaboration is difficult without the real-time collaboration (i.e. operational transformation) technology. To do this, a collaboration server must be run, and operational costs such as roles, privileges, and security are involved.
It is not the direction of StarUML to become this large and complex toolset. Since StarUML pursues agile and concise modeling, it is not suitable for creating huge software models. Instead of writing one huge software model, we recommend writing several smaller software models for each key aspect of the entire software system.
Thank you,
StarUML Team