Per a press release from La Fondation du Grand-Duc et de la Grande-Duchesse:

“On the occasion of their marriage, His Royal Highness Hereditary Grand-Duke Guillaume of  Luxembourg and his fiancée, the Countess Stephanie de Lannoy, have expressed interest in supporting and develop social projects in Luxembourg. 

For this purpose, a special account, Mariage Princier – Projets sociaux au Luxembourg, were opened with the banking institutions BCEE and BIL…”

Please click here for more information regarding this new venture/project.

UPDATE:

Here are new photos of the couple along with their new official monogram.  Or, please click here to view a larger photo.

Source: La Fondation du Grand-Duc et de la Grande-Duchesse