Actually, even if the Ruanlin Family didn't mention it, Du Qing would have looked after Ruan Jiaojiao anyway. First, she genuinely liked her niece, and second, she had a very good relationship with Jiaojiao's mother. When the commune system was abolished, both she and Ruan Jianjun were out of work and living a difficult life. It was Shu Jiao, Jiaojiao's mother, who had been supporting them, even finding them jobs in town through her connections.
She would remember this kindness for a lifetime.
Now that Shu Jiao was not at home, she naturally wanted to take extra care of her endearing little niece.
After being affectionately held by her elder brother Ruan Hao for a while, Jiaojiao was taken back to the second room of the house by Du Qing. Du Qing placed her on a stool to stand, and as she took her measurements, she asked with a smile, "I heard Jiaojiao has become quite skilled, able to hunt pheasants now."