Where do you have that information from? And I don't fully understand your post - is it a question or is it something you've heard?
If it was a question: No, she was not attending the Holmenkollen Ski Festival events on Saturday and Sunday (10 - 11 March).
If it's something you've heard: The King and Princess Astrid will attend the Biathlon World Cup in Holmenkollen on Saturday and Sunday (17 - 18 March) - but I have not seen/heard anything about that Princess Beatrix will attend.
Has she attended before? Yes, she attended the Holmenkollen Ski Festival in 2014 as the King and Queen's guest.
More photos from the ''Killi-Olsen exhibition'' in the Queen Sonja Art Stable today - taken by Oskar Aanmoen: