Illegal occupancy ,house grabbing of a senior citizen

My mother in law got a property through registered will which is a nazool land along with one more adjacent land given to a trust by the same will.The will got probated and the land had been declared freehold in their names respectively.Meanwhile some land mafiyas trespassed the property.suit for possession is pending in hon high Court as lower court raised question on will which was not an issue and has been probated as well .Now the managing trusty of the adjacent land joined hands with trespassers and filed a FIR against us in 420 denying the POA given by him in 1999 and executed sale deed in their favour which has been entered into agreement for sale with us earlier.By this POA probate case is filed ,freehold deed is executed with his consent and affidavit ,and he is admitting the freehold deed in his sale deed which is executed by the same POA. Now they are black mailing us to leave our land in their favour.What to do now and what steps need to be taken.?