The following FAQ should cover the issues.
Q. I am a US Citizen. My parents (or spouse/spouse-to-be) are in USA on visitors visa. Can I apply for their green card? How does it all work?
WASHINGTON — The Department of Homeland Security (DHS) launched an enhanced Study in the States website Monday with four new features. The features enable the Student and Exchange Visitor Program (SEVP), housed within U.S. Immigration and Customs Enforcement's (ICE) Homeland Security Investigations (HSI), to convey pertinent information to stakeholders about the international student process in a clear and interactive manner.
The new features include: