There is a play, called "The Heir of Verchiel", performed yearly in Verchiel, that includes a character of "Countess Dionne", discussing a long lost son with Duke Le Seuille. It can be found as Volume III of the Codex entry: A Compendium of Orlesian Theater. It is unknown if the play is about this specific Countess, or perhaps one of her predecessors.
This section contains spoilers for: Dragon Age: Inquisition.
As part of Josephine Montilyet's effort to bring her family back into Val Royeaux, she needs the approval of an Orlesian noble, and so she approaches the Countess Dionne. The Countess wants the Inquisition to find her mage lover in exchange for her support. After bringing the Countess a letter, retrieved from Ellerly by the Inquisition soldiers who found him alive, she promises to help Josephine.