maybe Wang Xiangyang, Ya Qing et al. researched it and found out somehow?

I wonder if Zhu Jiu researched the whole SID, perhaps using Ding Dun or someone else with a similar investigatory power, before the Hanga Arc? He knows a lot about Wang Zheng's backstory, which is impressive given her amnesia. And then Zhu Jiu could have passed all his intel on to Ya Qing before he became a Ye Zun snack. Or, otoh, maybe Ya Qing decided to research everyone, and one of the Crows remembered seeing what happened to Da Qing.