Filing for divorce along with a Bigamy Case

My brother got married on 17 Feb 2018, and 15 March 2018 he left for Africa where he works and his wife left for Australia to meet her brother. After that she never came back to us and asked for a divorce stating she did not want to go to Africa. They signed a Mutual Divorce Deed in April 2018. However, our lawyer had advised we need to wait for 6 months before putting up the Divorce File in the Family Court. Now through a source we have come to know that the girl has got married to someone else. According to my knowledge this is a Crime as Bigamy is illegal in India. My question is, would filing a case of bigamy against this girl delay our proceedings of the divorce? Cause in the need of the divorce I would not want to let go of someone who falls under a punishable act. And can I (not the husband, but his sister), file a case against this after the divorce decree is received, because the crime was done before being divorced. Can she get married on the basis of the Divorce Deed? As this will lead to encouraging girls to commit such crimes as the law is a bit biased towards females, which I believe is not right.