(IDEX Online) - A son of the LVMH billionaire Bernard Arnault will reportedly take a key management role at Tiffany & Co.Alexandre Arnault, aged 28, is currently CEO of the German luxury suitcase brand Rimowa, which is part of the LVMH empire. Two brothers and a sister also run LVMH companies.His appointment, and that of Anthony Ledru, a top Louis Vuitton executive to another top position at Tiffany, have not been announced by LVMH, according to the Business of Fashion website, but have been confirmed by well-placed insiders.The $15.8bn acquisition of Tiffany is finally due to take place today (7 January) after LVMH dramatically pulled out last year, sparking a series of bitter legal threats.Earlier this week Alexandre Arnault, second son of the LVMH chairman and CEO, announced his engagement to Geraldine Guyot, founder of the French accessories brand D'Estree.Bernard Arnault's daughter Delphine, is executive vice president of Louis Vuitton, his son Antoine heads the leather goods company Berluti and another son, Frederic, is newly-appointed CEO at watch brand Tag Heuer.Instagram pic posted this week shows Alexandre Arnault and fianc?? (C)e Geraldine Guyot