• Depriving of property share of father who died intestate

Her father was born in Goa of Goan parents and his birth is registered in Goa, he got married in Bombay to a Goan, the latter was born and brought up in Bombay. He died in Bombay(Mumbai) was survived at that time by his wife and three sons and three daughters. He died without leaving a will, the properties owned between him and his wife were three plots in Goa and one apartment in Mumbai, the apartment was bought from his own funds, one plot was - according to his widow- purchased by her. One other plot was bought by him, but was sold (somehow), about 20 years ago, by the widow and the eldest daughter. Signatures were taken on some legal document at that time from all descendants citing requirement of funds to get the youngest daughter married. A copy of that document was never given to my friend in spite of several requests. The third plot is ancestral. According to property law in Goa, all properties of husband and wife are consolidated and thereafter each is a 50% owner. In this case the widow has right only on 50% of the property and the other 50% passes on to the lineal descendants, both boys and girls. Two of the male descendants have passed away, out of which only one has a child. For the third plot my friend was made to believe, the widow ‘gifted’ it away to one son, though she can gift only what is her’s by law (50% of the original). No further processing was done for this plot. 
It has now come to our knowledge that the widow (i.e., friends mother), the eldest daughter, the youngest son (friends sister and brother respectively) have been collecting documents to prepare a succession deed/certificate, for which they have collected documents from all parties stating false requirements including my friend. The beneficiaries of this Succession deed are supposed to be the male descendants and or their survivors, my friend and her family live in a different city due to professional requirements, not in Mumbai or Goa. My friend had sought copies of her father’s documents – birth, domicile, property, marriage, etc., but her mother –the widow refuses to provide any, citing non-availability.
Is there any way to get the required document copies? From reading and research we have come to know that all lineal descendants’ information has to be part of the details supplied for the succession document, since the land property/properties are in Goa, the application for succession deed would be filed in civil court in the district where the father was born. Newspaper advertisements would be put out. My friend is worried that she would never know of its publication and even if she did know and wanted to contest for her rightful share, what documentation and recourse does she have?