I noticed marriage was not mentioned between your stepdaughter and her bf. If it is not on the table right now, you need to prepare your stepdaughter to be separated from her bf for a while. The only way for him to properly immigrate is as her husband.
That is not going to happen. It is almost a guarantee that he is not going to get a tourist visa. You, me, and everybody here knows that if he was to get a tourist visa, he will use it to migrate, which is illegal. If a bunch of strangers on an internet forum can suspect his plan for the tourist visa, an experienced officer will see it a mile away.
Yes, you need to make a decision. Time is not on her side. She reaches 21 and it is another ball game.
Listen, she is young. She was not thinking about long term plans when she wanted to stay behind to finish school. She was probably only thinking about her friends and social groups. Things have changed now, she has a baby to think about. The decisions she makes need to be well thought out and there should definitely be an understanding of the ramification of those decisions.
Talk to her about the options. Make her realize this will not be an easy process and there are no short cuts. Sacrifices will have to be made.
OP, you have wasted a lot of time doing this based on you post from last year. I'm not going to dig thru your old post but people here want to help you.
What was the age of the daughter at the time of marriage?
What is the daughter's birthday?