Proving a Hindu Marriage

Hindu marriage took place in November 1996, First child born May 1998 and second child born in October 2000. Girl moved overseas, abandoned the kids and married again over there in 2004 claiming as "Never Married" She also changed her last name and first husbands name was put on her passport. Now, she has separated from 2nd husband and trying to claim money. She claims that her first marriage was void, a lawyer gave a letter in 2004-2005 stating some false facts about her first marriage and she is basing her conclusion of getting married again and saying on the form 'Never Married' on that lawyers letter . Is it possible to get a solid proof of her first marriage, in laws and her parents are not ready to help. Some sort of civil and criminal case was also put against the first husband around 2000 and divorce case around 2003 but no further details are available to get case details. Is there any way to prove that she was legally married in India, she had two kids and lived with the husband for almost 4 years so how can she say it was void as she was forced in to it etc.. Thanks