I don't think a princess from a reigning royal house would get much traction but it could be interesting. Now, Caroline of Monaco had some traction when she sued the German press in 2004, but she lost in 2012.
2004 case: https://www.pinsentmasons.com/out-law/news/princess-caroline-of-monaco-wins-privacy-ruling
2012 case: https://www.bbc.com/news/world-europe-16933815
If Durek's mother is telling the truth, then Durek misrepresented himself not only to Martha-Louise, but to her parents and family as well as his followers and patrons. That classmate of Durek's has verified Durek's version, so that carries some weight in his favor. Durek could sue his mother for defamation, but I don't know anything about the defamation laws in Norway. Can she be sued for remembering things differently? Her comment about Martha-Louise being "brainwashed" only reflects what so many people already think.
===
184