A story built around an anonymous source is not automatically false, as you imply.
Anonymous sources helped bring down Richard Nixon, and have helped shed light on many other political misdeeds.
Conversely, an anonymous source isn't automatically true. Politicians are skilled at manipulating journalists for their own expedient purposes.
Sources only point reporters in a certain direction. What the press uncovers can be used in more formal investigatory proceedings, with stricter rules for sifting fact from fantasy.
The press part is the easy part for Trump and his family. Once the Senate and House bloodhounds are totally engaged, Jared is going to have to find a tree to climb pretty quickly.