Thus far, I have seen the following has confirmed their attendance:
- The Norwegian royal family, including Princess Märtha Louise (and probably her fiancé) and Princess Astrid Mrs Ferner.
- King Willem Alexander and Queen Maxima of the netherlands, with Princess Catharina-Amalia
- Crown Princess Victoria and Prince Daniel of Sweden

Nothing official from Denmark, but the Crown Prince couple (possibly accompanied by Prince Christian) will probably attend.
The Spanish King is a godfather of the Princess, but he appears to have other engagements this weekend. The Belgian King is also otherways engaged (in Romania).