Illegal wife and her rights on properties of

My brother was an employee of Regn Dept from 1973 and deserted our family and married a girl at Ariyalur without consulting myself and my parents lived at Ariyalur. Within a week he had sent out the lady to her parent as he was having an illegal connection with a lady co worker.From 1981 he was keeing her as wife and lived at Vandalur till 2001. In 2001,he had sent out the second wife also by executing a release deed with that of Co worker lady and got the deed registerd in the registraion Dept. He married another lady withot informing me or any others of my family and continued to live with her in the same house at Vandalur..He has got ration card etc. at Vandalur itsef. From 1981 to 2014 he never visited our native place due to fear about the first wife at Ariyalur. Lastly he had visited to my sister's house at Ariyalur to attend the funeral function of my sister's husband death. in the last week of March,2017 he came to my sister's house at Ariyalu and taking treatment. On 10-4-2017 suddenly he died at the Hospital. Last rites were performed by me at Ariyalur as my brother had no son or daughter.We all were under the belief that the lady who had come from Chennai is his Wife. Susequent made revealed that the present lady( aged 48) is already having a husband and after deserting him she she started living with my brother. Now it is understood that she had obtained a legal heir-ship certificate from VAO of Vandalur stating that she is wife and male child born through her first husband is also a legal heir of the deceased. As we had no connection with the deceased for nearly 40 years we are unable to ascertain the details of her family and her first husband. The decesed native place is Ariyalur where he died. Kindly clarify who has to issue LHC eithe VAO Vandalur or Ariyalur where the death occurred. The decesed had never took part in any functions at aRiyalur never spent any money for his father,mother, sisters etc. All were taken care by myself for nearly 350years. There are ancestral properties at Ariyalur.Kindly advice me on the course of action to be taken by me to protect the interest of my sisters and my children