Madonna is such a proud mum! The award-winning singer took to Instagram on Monday to reveal some incredible photos taken by her daughter Mercy James – and fans were more than impressed! MORE: Madonna's son David dances inside star's incredible kitchenThe mother-of-six shared a series of portraits that Mercy had taken of her younger sisters Stella and Estere, including black-and-white headshots and some beautiful close-up pictures of the twins wearing co-ordinating bandanas.Fans were quick to