Understanding one
The word "raise" means "live" in Jianghuai area. For example, when the Zhang family gave birth to a child, they said that "the Zhang family has a son". Therefore, foster brother-in-law refers to the offspring born after incest between daughter-in-law and father-in-law. Imagine: in such a society, such a big family, which brother-in-law depends on his sister-in-law? How does a sister-in-law support her brother-in-law So don't get me wrong, or the more we discuss it, the less clear it becomes. The word "keeping" in A Dream of Red Mansions really means keeping in good health. For example, Jia Huan said, "You all bully me because my wife didn't support me." Tan Chun said, "Who doesn't know that I was raised by menstruation?" Therefore, adopting a brother-in-law refers to the illegitimate child of a daughter-in-law and her father-in-law. Jiao Da yelled at Jia Rong, which means scolding Jia Rong: "You idiot, you didn't know that your father was cuckolded!" So this sentence is aimed at the relationship between Ke Qing and Jia Zhen. Who knows if he killed himself because he found out he was pregnant?
Understanding 2
In JOE edition, Jiao Da said "foster brother-in-law, foster brother-in-law" followed by four words: "including Xiong Bao". This sentence refers to Baoyu. So let's see whose brother-in-law Baoyu is and whose sister-in-law Baoyu is. Baoyu's sisters-in-law in the book are mainly three: Li Wan, Wang Xifeng and You Shi. Judging from the description in the book, these three people have no such relationship with Baoyu. Among them, the closest relationship with Baoyu is undoubtedly Wang Xifeng, and everyone can see it. So I guess, because Jiao Da knows the inside story of Ningfu, he knows what happened between Jia Zhen and Ke Qing, so when he saw the seemingly intimate state between Wang Xifeng and Baoyu, he would naturally associate it with adultery between their uncles. But Jiao Da is not in Fu Rong after all, and he doesn't know the real situation. His idea is only a subjective guess made from superficial phenomena. Jiao Da was drunk and delirious at that time, so he didn't close the door when he spoke, so he shouted out what he was thinking, whether it was true or not, and even described "white knife goes in, red knife comes out" as "red knife goes in, white knife comes out", which should be understandable. Later, Wang Xifeng also said to Baoyu that "it's all because of drunkenness." On the surface, Wang Xifeng means "climbing the ashes", but in her mind, I'm afraid it means "raising a brother-in-law, raising a brother-in-law".