remember feng feng and yi yun both submitted sperm to that foreign company to have a child through a surrogate mother. feng feng was nearly killed by family fighting for power. so he used his power to swap his and yi yun's so that feng feng could continue his family line safely. feng feng hadn't told yi yun yet, but he had yi yun's stored to give back later but feng feng's family found out and stole it. at the time no one knew yi yun was from the he family, so there was no value in stealing his child. they thought it was feng feng's and feng feng thought it was someone from his family trying to hold onto his weakness. feng feng was investigating and waiting to tell yi yun when he got it back but he was having trouble tracing it.
later we saw feng feng's aunt. if i remember, she was in an accident or something and couldn't have a child so no one considered her to be a possible successor. she used a surrogate mother to birth a child that she believes has her family's bloodline. this is yi yun's lost child.
WAIT WHAT SOMEONE PLEASE EXPLAIN THERES ANOTHER BABY?!?