Is Koharu a new singer in the Korean drama Thank You?

This is a biological child, a child of Yongxin and Xuan Shi. He was born because Xuan Shi and his friends had sex when they were betting whether he could get Yongxin. . . Yongxin liked Xuan Shi at that time. Later, Yongxin and Xuanshi made it clear to each other, but Yongxin didn't want to have anything to do with Xuanshi. She wants Xuan Shi out of her life. She said that Koharu was her child, not Xuan Shi's daughter. . .