Maggai

My friend got married in 1999 in Ghana. He is currently a US citizen.
His wife got to the USA about two years ago on a tourist visa, because
he was still a LPR then. She did not indicated that her husband is in
the US at the time she was applying for the Visa. She has been out of
status for quite sometime now.
They just had a baby girl. Two months ago the husband became a US
citizen.
Now the question is, how does he go about adjusting his spouse status.
Could someone please advise on this.

Thank you.