The 26-year-old's brother Robert Irwin explained that his sister could not attend the annual Steve Irwin Gala—celebrating ... with our families smiling and laughing by the lake," Bindi captioned ...

Eighteen years after Steve Irwin's tragic death at the age of 44 ... "We spent this day with our families smiling and laughing by the lake," Bindi captioned this photo from 2015.