This is a fraud: using a visa not for its intended purposes. You can get into a lot of trouble for that. NEVER, NEVER do that...
He should go to her home country, get married, and let her apply for a H4 visit in consular office in her home country. She can come to US to join you using H4.
He can file for i485 NOW. Later on he can send in an application to add his wife's name to his 485's application.
As long as he adds his wife's name BEFORE his 485 is approved, they will be under AOS pending status and can stay here until approval.
I went throught the whole process myself. I and my wife are now waiting for 485 approval.
