Extortion by wife

My name is Rajesh Kumar Dhillon. I am Chartered Accountant and settled in Delhi. I am giving a brief about case below. I hope, you will guide to proceed it further. -My wife have two brothers. Both are married and live in village in Bhiwani district. -One was married 10 year (apox) back and younger was married 3-4 year back. -Younger worked in BPO from 4-5 years. -They are financially not strong. -Younger worked for 4-5 years in a BPO and bring his wife in Delhi. -But 6-7 month back, he suffered a loss in his personal business and was not able to keep his wife in Delhi and dropped her in village. -Now his wife and wife's father are demanding 15-20 lacs from them to settle. -They do not have such a big amount and getting daily call from them. -I hope, they are going to file a case or perhaps they have file a application today. -They want to file a complaint/case including me and my wife. I would request to guide, how to take it further by me, my family and their family.