As Donald Trump prepares for a return to the world stage, all eyes are on Washington DC and the President's family and close allies. But one in-law cuts an especially elusive figure.

Ines Knauss, the 53-year-old sister of Melania Trump, hasn’t been photographed in 20 years - not even at the funeral of their mother last January or her brother-in-law’s first inauguration in 2017.