So when Yi Yun wanted a baby, he got an embryo inseminated. However, Jinyao needed Yi Yun to raise his child so instead of letting this embryo gestate, he switched the embryo to one that was inseminated by himself and let this become Rourou.
Jinyao felt kinda bad for doing this in the first place, so he stored away Yi Yun's embryo for safekeeping in order for Yiyun to be able to have a biological child later on (with the embryo he'd originally chosen for himself). This embryo has since been stolen cuz the ones who stole it (*cough* his aunt *cough*) thought it belonged to Jinyao, and wanted to prevent him from have a first born (cuz the child would automatically be an heir being first born of an first born)
OHHHH OK TYSM!!
Plz what ok wait so I’m confused. He got yi a surrogate so he can have a biological child??? (〜￣△￣)〜 ……what????