Whether Emperor Cheng was formally "adopting" Prince Xin would quickly become a major controversy. Emperor Cheng viewed his creation of Prince Xin as crown prince as formal adoption, and he believed that Prince Xin was now his son, no longer Prince Kang's. When he created a cousin to be the new prince of Dingtao to serve as Prince Kang's heir in winter 8 BCE, Prince Xin, grateful that his father would continue to be worshipped as an ancestor, submitted a formal note of thanksgiving—at which Emperor Cheng was highly offended, believing that Prince Xin should not be grateful any more for whatever is done for his birth father.