Dian had her suspicions about the Montreal twins the moment she saw them and such suspicions aggravated when she heard her own mother's comment about the children in the Loch. Truth was, like Dannah she had long had the children investigated and found nothing that can confirm her raging suspicions. But right then she was sure with her facts.
When she emphasized the truth that Wolfe was a Lagdameo, she didn't find any surprise on the faces of the people in front of her and all she could see was the worry and frustration they had over the situation. Right then she realized, they had long known the identity of the children. Was she the only one who didn't know then just until recently? Does this mean both Darryl and Dannah learned of it and intentionally hid it from her? How dare! She had put spies in all of L'Empire to make sure to catch information like this and yet no reports about the children being Lagdameo was reported to her.