Well, first do NOT start a public discussion to ask for help ...
Oh well, assuming the real issue is the father of the child is not the same man as the future husband? Add a partner to the female relative then give that new partner a child then delete the partner. This will leave your female relative with a husband (and any children that you've added to that couple) and a child linked only to her, this child will display as a stepchild of the husband and stepsibling of any other children.
Give it a go, if you have any trouble you can send me a private message with some more details and i will sort it for you over the weekend.
