Nearly every morning since their father's stunning victory on Election Day, three of Donald Trump's grown children walk through the Trump Tower lobby and board an elevator. But are Don Jr., Ivanka and Eric going to the campaign office on the fifth floor? Their business offices on the 25th floor? The president-elect's penthouse on the 56th floor? That uncertainty highlights the multiple roles the children play for their father. For the past year, the lines were constantly blurred between political campaign and business empire, raising questions about a possible conflict of interest between Trump's White House and his sprawling business...