Teen (Christina) De Gernier, born 1890, was an older sister of my granny, Mary Ann who was born in 1896 in Dundee.Teen did work on the buster stalls in Dundee.Their father was Gustav (or Augusto?). His father was named as Thomas (also Antoine?) and his mother was Hortense Camilla Verplancke on Gustav's marriage certificate.
I believe that Gustav went to Australia in the early 1900s.
I have also found a William Henderson in my research and wonder if he is any relation to your great great granny and grandfather in the photograph.