Sale Deed From Late Father To His Wife And Son Possibility

Currently, we are leaving in the house which is on my late father's name(allotment letter). We are having his Registered Will and his wife's Notarized Will. I am his son and we do not having good relation with my brother. So below are my doubts and will be very happy if someone can help to answer it. 1) Is that other son can able to challenge this Will or how strong these Will's can be. 2) Can we make a Sale deed on my mother and my name(joint). Kindly let me know if any other positive possibilities. Thank You