Hailey Bieber took to Instagram on Tuesday, August 17 to share a sweet tribute to her niece, Iris Elle, in honor of her first birthday.“Happy first birthday to our beautiful smushy girl,” the model wrote on her Instagram Story, adding, “Aunty and uncle love you so much!’Below the text, the 24-year-old included a black-and-white photo of her and her husband, Justin Bieber, sweetly kissing on each of the little one’s cheeks.Iris is the child of Hailey’s older sister Alaia Baldwin and her husband