Does married daughters have equal legal right on father's propert

My maternal grandfather had a two storied house. He has three daughters(all married ) and a son(married ). Before his death (20 years ago), my grandfather made a will but probate was not taken. In the will, it's written that the elder and the younger daughter will not get any portion of the property as they don't need. But the second daughter will get a backward portion of the house and the son will get the rest of the house after my grandmother's death. No mutation of the house done yet after death of my grand father. Although the will was not send to the court to take probate, my question is : 1)Does the will have any legal importance? 2)Will the three daughters and the son get equal portions of the house? 3)All of the siblings were born after 1956 but before 2005. To take probhet of that will, does everyone of the heirs need to agree? 4)Can the son get the entire house, after my grandmother's death without giving any portion to the daughters? 5)Can my grandmother (alive now) legally give off her portion to anyone? 6) Can my grandmother make a new will?