secretly married

So I have a friend whose been in a relationship on and off with her childs father, majority of the time still living together. They still live together now but she's been in a relationship with a guy for almost 2 years. he has a wife who he doesn't love anymore and she filed for divorce. he wants to marry my friend but she's stuck living with her childs father and I guess he told her if she divorced him he may be deported to his country. so I'm guessing they don't have much time to marry before that happens, is there a way for my friend and him to marry without her child's father knowing until she moves out??