Over the past few years, Delilah Belle Hamlin and Amelia Gray Hamlin have made jaws drop while attending New York Fashion Week in gorgeous (oftentimes coordinated) looks, and this year’s Harper’s Bazaar Icons party was no exception.

For the September 9 event at Bloomingdale’s 59th Street flagship location, Lisa Rinna’s daughters hit the red carpet in sizzling black ensembles. Delilah paired Grace Ling’s Vertebrae Bralette ($370) with the designer’s Pillar Drape Skirt featuring a square lower back plate ($990). Hairstylist Laura Rugetti gave Delilah’s (recently dyed) hair a chic slicked-back look and wrote in an Instagram post that she added Glam Seamless Hair Extensions clip-ins “for extra length.”

Amelia donned a floor-length leather Givenchy dress with small…