Love4ver,
You may have a problem with the boy. He can apply for adjustment of status as a derivative of his mother's application for adjustment of status. But she hasn't yet applied for adjustment of status? And if she does apply she will abandon her applicationby leaving the USA without advance parole? Either way may lose the boy a basis to adjust status.
Filing an I-130 for the boy as pushbrk suggests may solve the problem, I don't know.
I think you might want to consult with an immigration attorney before you and your wife take any further actions that you may come to regret.
Yodrak
If not, your fiancee might want to look into
QUOTE(Love4ver @ May 2 2007, 01:41 PM)

Hi,
My fiancee and my step-son came to America 3 weeks ago through an I-129F I filed for them and she needs to go back home bcos her father was seriously ill and she is the only child. She is going back next week but she wants to leave her 2-years son with me which I have no problem since my sister would be taking care of him, how can I make the son legal or what form should file for him ? If need be I can adopt him. I already filed I-130 for the mother to come back to the State.
Help me, and thanks in advance.