Any sale of ancestral property without consent of all legal heirs is invalid and liable to set aside. There is no limitation for seeking sale of property by legal heirs not giving consent to sale by any of other legal heirs. All four father, mother and siblings have equal share in the property. Except to the extent of his share that is ¼ sale of ¾ is not binding on non consenting legal heirs. Property is in acres, it seems to be located around Hyderabad in RR District. Issue lawyer’s notice to all legal heirs seeking partition and separate possession of property. After that file a suit in district Court for partition and separate possession. Add all purchasers as parties to the suit and submit certified copies all sale deeds executed by him. Seek cancellation of all sale deeds in favor of third parties. You are not bound to return the sale consideration received by father as it was no applied for the betterment of family.