Children adopted as toddlers---rather than infants---often have their first names unchanged. I think it unlikely that the middle name would also be unchanged. Of course, after legal adoption, the surname is changed to that of the adoptive father.

The website known as PrivateEye allows one to search without knowing the current surname if one knows the exact date of birth. There were three hits for women named Stephanie Marie, born 01-16-1983, now living in Rhode Island. I chose to search that state only. There was only one hit for 01-16-1984, but the middle name did not match.

Reg Niles