亞曼達·塞佛瑞德彈奏擊弦古提琴並開唱！潔賓娜·卡本特該不該加入《媽媽咪呀！3》？ (Amanda Seyfried Sings & Plays the Dulcimer, Says Sabrina Carpenter Should Join the Mamma Mia! 3 Cast)