Regarding Will

As recently by grany died , My father was only son & Am only son , apart from that my father has 3 sisters, 1 residing in foriegn country 2 are in Delhi, after the death of my grany we were threatened by my aunts (My father sisters) to grab the property although my grand father before die in 2001 gave few documents to my aunt in foreign & few documents to my father, so that the property may not be sold out (this is what I understood) & before my grany died she made a will in favor of my father and also filed a nominee my father in her banks before her death occurred. We have occupied the property and is under our power. Now what is happening my aunts are threatening & abusing us, so, I have also filed a complaint at police station twice. I have been residing at the same property since my childhood. now I am 29 yrs old. Now, the will is on a plain paper with my grand mother signature on it and photograph attached of her on it with her will in favor of my father, registered in court earlier her death and 2 witnesses and 1 witness of advocate itself. Will is in favor of my father. Now I want to make it strong , so that no one in the future may challenge us. Please guide.