RIP Christian Oliver. On Sunday, January 7, Mauricio Umansky took to Instagram to mourn his The Agency coworker after his tragic death on Thursday, January 4. “Christian, Madita and Annik, you will be missed,” the 53-year-old wrote of Oliver and his two daughters who sadly passed away in a plane crash. “May you rest in peace.” Umansky added: “My prayers are with you and your entire Agency family. You are a great friend, father, husband, actor and agent. You made us laugh, you care more than most. You are missed and loved.” The Real Housewives of Beverly Hills star also added an audio snippet o…