Share in ancestral property.

The property approximately area 7 acres given by my Great Grand mother to my Grand father After death of my grandfather it passed on to his wife. My grandfather was having 3 sons and 2 daughters including my father .Among the sons my father and one of his younger brother expired and 2 daughters also expired recently. After my father’s death his both brothers sold some area of the property to Mr. Shenoy in 2002.For the sale they have not taken consent from our family and family of other 2 daughters. Few years back in 2010, 2nd brothers son sold another portion of land to third party and started garment shop on partnership basis. Here also for the sale no consent had been taken from our family and family of other 2 daughters. Now in 2016, younger brother’s son had filed a case through GPA for partition against all of us and sale dated 2010 to be declared as forged. In the plaint plaintiff has made party to all except myself and my cousin. Except 2nd brothers family no one got notice from the court / advocates office about the filing of suit. Now the 2nd brother’s son is asking GPA from all of us to give us to fight case against younger brother’s son. Now I am having doubt that without court issuing notice can we give GPA. What is the procedure for partition and in such case how will I proceed .Younger brothers son is not ready for compromise. Please guide how will I proceed to get my share.