What was the first time big sister was kind to Adeline?

Big Sister was kind to Adeline for the first time after she warned her that Niang knew about the jade necklace.

I told her of the conversation I had overheard between Grand Aunt and Niang. Tears came to her eyes and she patted me fondly on my head. “I’ll never forget this kindness on your part. Thanks for the tip-off. You’re the best sister in the
world and I’ll always be indebted to you.”

For the first time she was kind to me, and I felt very close to her.