Not sure if this is even out there, although I hope so. What I'm after is a hack that allows you to choose the Surname of a child born to unmarried sims, as usually the game gives the child the mothers surname. Sometimes if the sims are living together then it would be better for the child to take the farther's surname.
So, is it out there? I've seen a similiar hack for marrying sims so hoping it's out there!