The aunt with a white hair and hair tied? (the youngest and second aunt) Fengfeng did tell that aunt is nice to him. Remember when Fengfeng exchange his (sperm) to Yiyun's? Yiyun supposedly be Rourou's biological father if Fengfeng did not interfere with the procedure.
Fengfeng still keep Yiyun (sperm) to storage but it was stolen (with intention that it was Fengfeng's) so the matter is... the Aunt apparently stole it and have the (sperm) became an offspring! Haha, 'ya know surrogate mother and stuff. That's why they said Rourou's gonna be a brother with YIYUN'S BIOLOGICAL SON.
The aunt with a white hair and hair tied? (the youngest and second aunt) Fengfeng did tell that aunt is nice to him. Remember when Fengfeng exchange his (sperm) to Yiyun's? Yiyun supposedly be Rourou's biological father if Fengfeng did not interfere with the procedure.
Fengfeng keep Yiyun (sperm) to storage but it was stolen (with intention that it was Fengfeng's) so the matter is... the Aunt apparently stole it and have the (sperm) became an offspring! Haha, 'ya know surrogate mother and stuff. That's why they said Rourou's gonna be brother with YIYUN'S BIOLOGICAL SON.
(That's all, you must have forgotten about it because it's been long)

Spoiler alert
Apparently Fengfeng nice aunt(Idk if she's still that) is the one who took Yiyun's fertilized embryo thinking it's Yinyao's.I think the baby is gonna be born soon.. Omg the drama! Rourou is going to be a big brother
This is next week issue..