What is the relationship between the glory of Shen Zhenzhu in the Tang Dynasty and the settlement of An Qingxu?

An Lushan's wife and Shen Zhenzhu's mother are good friends and sisters. She met An Lushan on a business trip and married An Lushan. Later, she couldn't stand An Lushan's tyrannical temper. In a rage, she returned to Xing Wu with her son An Qingxu and lived alone with her good sister yang shen. In those years, An Qingxu followed her mother to Shenyang and grew up with Shen Zhenzhu. This relationship is natural and profound. An Qingxu likes Shen Zhenzhu since he was a child. Because of this relationship, Shen Zhenzhu called An Lushan uncle.