I told the girl that this is your second child, and she replied that I have that ability. What should we do next?

You can answer: that depends on whether you are willing to give this opportunity.

This is a humorous and respectful answer, which not only expresses goodwill but also gives the other party the right to choose. You can often see similar conversations on the internet, and this kind of answer is considered to be both interesting and polite. But please remember that everyone has their own feelings and comfort zones, so when having such a conversation, we must respect each other's feelings.