Is “Dou Jiannde's daughter, Princess Yong'an, Dou Xianniang” true?

In "The Romance of the Sui and Tang Dynasties," Dou Jiande's daughter Dou Xianniang is portrayed as a distinctive female general. The book states: "小女线娘，年方十三，色艺双绝，好读韬略，闺中时舞一剑，竟若游龙。" (The Romance of the Sui and Tang Dynasties, 026.txt) It describes her as skilled in using the Fangtian halberd and golden pellets, and she forms a marital bond with Luo Cheng on the battlefield. However, consulting the official histories such as the "Old Book of Tang" and the "New Book of Tang," there is no record of Dou Jiande having such a daughter. This character is purely a fictional creation by the novelist to enhance the romantic flavor of the romance.