Inherited land and property

Our grand father died last October. My father and my grandmother died a long time ago... My deceased grandfather left a large estate. The problem is, our tito's and tita's seem to do not care about us... They haven't done anything yet to talk to us. Now, my brothers and sisters are already of legal age except one... We have always been left out even when they had sold hectares of land a long time ago with only my mother's knowledge as a guardian and a signatory. During that time, my grandfather was still alive. What should my brothers and sisters do? It is in fact our legal right... Thank you.