To marry a foreigner in india.

I shall be thankful to you, if you could, guide me on the following matters related to my Son. My Son is a 26 years old Indian citizen / origin by birth. (Birth Place Ahmedabad, Gujarat State). In 2009 he left for New Zealand on Student Visa valid for 2 years. Due to some unavoidable circumstance, he could not get his visa renewed / extended and since 2011 to January 2016 he lived there with out a valid visa. 14 Months back, he started living with a New Zealand citizen girl. She was married and a mother of a 1.5 yrs old boy. Her husband was a an Indian origin but had to left New Zealand (deported to India after being caught by immigration dept. as Overstayer.) Now he is in India. The validity of their marriage is due on May 19th 2016 (i.e. 2 years after marriage). My son accepted her as his life partner and lived with her and kid. In Sept. 2015, she gave birth to a baby boy. Now he is 5 months old. In January 2016, my son submitted his application Under Section 61 to grant a Visa. But immigration of New Zealand has denied the same and deported him to Indian. Now, my son want to bring his partner (de facto partner) and the two kids here in India on permanent basis. After her earlier marriage due is over (19th May 2016), he want to marry her in India. Can you please give me your valued advice on the above or give the details of person in Ahmedabad, Gujarat State to contact. Awaiting your valued reply. Regards, SKN