Both York princesses were there with their husbands.
I guess Forrest meant the recent wedding of Pr.Philippos.
From the Royal Houses you ask, only Pr.Kyrill of Bulgaria attended. BTW he is Philippos' godfather.
From Denmark, surprisingly only Queen Margreth's sister Pr.Benedikte and her elder daughter Alexandra, and son-in-law, Michael Greve Ahlefeldt-Laurvig-Bille.
No other balkanic nor russian royals.
May be the Grand-Duke is still on his honey moon . No idea about his Mother.
Nobody from Norway or Sweden, Benelux or Liechtenstein. Andrea Casiraghi and Tatiana surely attended on personal basis and not representing Monaco.
From the German houses, only the Hannovers.
Who of the European royals attended the wedding? Did any royals from Montenegro, Albania, Bulgaria or Romania attend? Or the Grand Duke of Russia? The English royal sisters looked lovely. The pictures did depict Queen Sophia and her sister Irene and there some royals from Denmark. The cathedral in which the ceremony was held is gorgeous.
Easy to Google “wedding of Constantine II”: https://en.wikipedia.org/wiki/Wedding_of_Constantine_II_of_Greece_and_Anne-Marie_of_Denmark