They already have a father. The parents should have thought twice about having a kid if they weren't going to stay together. It makes zero sense to be a father and raise someone else's kid if you can find a girl without children and then have your own children with her. The only reason men do it is because they're desperate and have no better options. I'd rather be single or move to a foreign country than go down that route, but to each their own.
You should understand, not everything is about you.