When Li Aihua was pregnant with her, she was only eighteen and unwed. Despite the harsh conditions, she still gave birth to her, which actually shows that Li Aihua did care for her.
Because Fang Pingying had seen some city folks sent down to the countryside in her childhood, many of these educated youths engaged in forbidden romance. But most people facing such a situation would choose to terminate the pregnancy.
Li Aihua insisted on giving birth, which comparatively speaks to a responsible attitude.
Moreover, Fang Pingying was aware that although Li Aihua went abroad afterward, she still had the man send money every month, not neglecting her.
So, although Li Aihua did wrong, if Fang Pingying is willing to be magnanimous, there's nothing unforgivable.
But as for acknowledging it or not, it's fine to leave it as is for now.
If Li Aihua wants to come, let her. Fang Pingying wouldn't be nasty to her, but she can't immediately call out "Mom" without any reservations.
