Taylor Swift treated two girls caught up in a stabbing at a dance class based on her choreography to a “magical” night at one of her concerts. The singer, 34, said she was left in “complete shock” after three little girls were killed at a Taylor-themed lesson in Southport, Merseyside, last month, and is since said to have reached out to families involved in the carnage. One mother Sami Foster has posted a now-viral TikTok video featuring a carousel of photos from a backstage visit to one of Taylor’s sold-out ‘Eras Tour’ shows at Wembley stadium, London, along with her girls Hope and Autumn. Ta…