Illegal transfer of property

Summary- We have our House constructed in in the year 1966 having a licence from Camara de Municipal Goa which was granted to my granny Late Rosa C. Cardoso. She kept her brother namely Antonio to stay with her who then married Benedita. Upon the death of Antonio, Benedita transfered the property to her name by paying bribe to officials(which we got to know now). Now Benedita has married a 2nd time to person named Agusto. She makes an Agreement of Sale in year 1983 showing she is the widow of Antonio, with a woman named Terezinha. In the year 1984 Benedita makes a Sale Deed with the same woman but shows she is the wife of Agusto. As per the Agreement of Sale & Sale Deed it says, Benedita has sold a residential house to Terezinha in this Sy.No.119/13. But the only house standing is our house and a store room outside. As per the Survey plan, when the deeds were done only our house was shown on it not even the store room. Now Terezinha has got d store room a House No., Electric & water connection and has laid laterite stones as a boundary and says the property belongs to her as well as the store room My Questions 1- How can Benedita tranfer the property to her name when the House was constructed by Rosa? 2- How can Terezinha purchase a house which belongs to Rosa without her consent? And even though she purchased the said residential house, how can she say the property belongs to her and tell us to do a partion to it? 3- If Benedita married another person having no children from her late husband does she have the right to sell the property of her deceased husband? 4-Should i challenge the Sale Deed made, in court? 5- What are the chances of winning the case? 6- The property in this Survey number measures 300sq.mtrs.Our house has 150sq.mtrs of it and the store is just behind our house leaving a space of 2&1/2sq.mtrs. 7- Under what Sections should i file the case or lodge a complaint against them?