Indeed had a child together

Yin Heng pondered over it for a moment before asking, "When will Madam return?"

"Madam was sent on a business trip by the President this time, and it will probably take at least a week," Ah-Zhong answered.

The corners of Yin Heng's mouth turned up. "Good. When Mother returns, I will give Mother a big present… I will investigate what Mother wasn't able to find out myself!"

If Yin Heng discovered that Yi Yunmo was being impersonated, then the person he wanted to assassinate wasn't the president's daughter. This way, if the assassination was attributed to him, Yi Lingjun wouldn't do anything to him, and the risk to him would be removed.

Moreover, if that woman really was an impostor, he could say he was eliminating a spy. Not only would he not be in the wrong but he would've also performed a meritorious deed.