Two wifes one son before marrage what are the rights of kids?

I am from Jammu. My Grand father own a farming land which was inherited from his mother's family. Then my grandfather married to my grand ma and had 3 sons and 5 daughters. In between My grand ma's little sister got pregnant by my Grand pa and her family left her in my Grand pa's family there was no formal marriage happened as she requested her elder sister to keep her in house and she will stay in whatever conditions possible. and My grand father produced 4 boys and 1 girl out of her so total 13 kids. 8 from married wife and 5 from non married wife. Now question is what rights do the 5 kids hold on the inherited property of my Grand father? as every one is claiming his rights on the property. Can you please guide me what rights every one has on this land as this is inherited property not purchased by my grand father. None of the grandmothers or Grandfather is alive. This is the time when we have to divide the land to its real owners as every one is threatening and trying to capture land here and there. Please advise. Thanks for your advice in advance.