Got confused

Rourou is the biological son of Feng and Jinyao is his caretaker. In the beginning Jiyao thought he was the biological dad of rourou bc he did't know that they switched their sperms when the baby was conceived. So Rourou is their son but in different term

So I am also a bit confused but here is my guess also please try to make our names since I forget sometimes: Rourou is biologically rich dudes but was raised by YiYi somehow I think rich dude replaced the sperm (or whatever you call it) with his own for some reason. Also this is a guess hope this was of use.

basically Rourou is Jinyao’s kid dna wise, and Yi’s child legally

Fengfeng is proven to be the biological/real father of Rourou (some unintended sperm sample switching mishap happened at the lab when Rourou was conceived).
But Yiyi is (falsely) believed to be the biological father (in paper only, i.e. lab records and certificate), ergo, still Rourou’s LEGAL father (though not biologically).

Correction: it’s not unintended; Jinyao deliberately ordered to get their sperms switched in the lab. Though he is a nice guy and it is clear as day that he likes Yi yun, this is most likely the issue that will cause major problems in their relationship later on.

I wrote unintended because remember, Jinyao changes his mind last minute not to have Yiyun’s sperm to be replaced by his but there was an “accident”

What accident? I clearly remember what happened: Jinyao and Yi yun ended up in the same clinic. And as Yi yun is the only Asian aside from him undergoing the same procedure, Jinyao picked him and ordered to get their semen exchanged. Then he initially ordered Yi yun’s sperm to be disposed, but changed his mind at the last minute and ordered to freeze it instead. Now Yi yun’s sperm is missing. I don’t recall any accidents happening

Yep facts 100%..I hope it doesn't cause a problem in the future but I guess it's inevitable