Is Yu Gege really a Gege?

According to the query of Douban app, Yu Gege refers to the role of Princess Pearl in the play, the daughter of Emperor Qianlong in the play, and the real princess. Emperor Qianlong's princess who traveled to the east once married a woman, Xia Dewu, and gave birth to a daughter. Many years later, Xia died of illness. Wei Zi and Jin Suo, the servant girl, came all the way from Jiangnan to meet their long-lost father with the keepsake left by Gan Long.