Access to the diagram's objects in Capella Studio

Hi,
I want to manipulate the object of the diagrams for the purpose of detect if there is already a generated one. If it’s existing I want to open it and not create a new one. My global purpose is to automated the generation of the diagrams. But I can’t get access to the SemanticElement. I have access to getDiagramRepresentation but it’s not the real object, it’s just informations related to it and I didn’t found any link to the object…Maybe I don’t understand something…If anyone has some clues, I would take them with pleasure!