Prince Jean-Christophe Napoleon has married Countess Olympia von Arco-Zinneberg, a great-granddaughter of Kaiser Karl of Austria, with a large portion of the Gotha in attendance for the religious ceremony. The only linkable articles I could find are from British tabloids, so they focus on the attendance of Princess Beatrice of York and her fiance, but the reigning houses of Luxembourg, Belgium and Liechtenstein were well represented, as were a whole host of non-reigning houses, including the Two Sicilies (maternal family of the groom), the Habsburgs (family of the bride), Greece, Yugoslavia, Portugal, etc., etc.

https://www.gettyimages.no/detail/news-photo/prince-jean-christophe-napoleon-and he-his-wife-olympia-von-news-photo/1182029210?fbclid=IwAR1esWuUKte4F6Gn0VeegN1xybu_EMzFfHPgF0IheYjOOdhyyY7WNyl9G8U

https://www.mirror.co.uk/3am/celebrity-news/prince-jean-christophe-napoleon-bonaparte-20653588

https://www.dailymail.co.uk/news/article-7590997/Napoleon-Bonapartes-descendent-marries-great-great-great-niece-French-Emperors-wife.html