When one enlightened person inserts his penis into another enlightened person’s vagina, that is considered an attachment. He is attaching himself to her, albeit temporarily. When he unattaches himself from her by removing his penis from her vagina, this is considered unattachment. So he is not attached to her any longer, and all is good with the world again. The same can be said about the umbilical cord. Soon after birth the child gets unattached from the mother, usually by hospital staff, so no Buddhist doctrines are violated again.

What a silly question! Of course enlightened people can have children! Stop reading stuff that tells you how you should live your life and realize that the only reason you are looking for answers is because you’re afraid to admit that there aren’t any, and you are the only thing that matters to yourself and it has always been this way. It can be extremely scary but very productive.