As of MagicDraw version 17.0.3, a used project in which the symbol style is defined is displayed next to the symbol style in the Project Options and Symbol Properties dialogs. This functionality also allows for copying a symbol style from a used project to the current project symbol style.
You can see the particular used project from which the symbol style is used and copy the symbol style from the used project.
In the example, you can see that in the project there are two Subsystem symbol styles - one style from the BPMN Profile.mdzip used project and the other from the UML_Standard_Profile.mdzip used project. The Subsystem symbol style from the BPMN Profile.mdzip used project is used in the current project.
The symbol style from used project is not editable because the used project by itself is read-only. By copying the symbol style from the used project to the project you can create a new symbol style and then edit it.
Note that there are no rules for the symbol style usage from used projects - symbols styles are used according to used projects loading order.
To copy a symbol style to the project style by using the Project Options dialog
To copy a symbol style from a used project in the Symbol Properties dialog