Ancestral property question

This question is entirely on my Mothers side of the family. 3 properties from my Moms Nana (Moms Grandfather on Mother side) 1) house in 1st phase, mohali 2) Madhanpur village property 3) property near village chappar chiri 1 property from Moms Father in Railon village Sirhind It was learned that my mothers father has created a Will in which all of this property is given to his brothers family. Because we are currently (my mother and our family) residing in Canada, my cousins were taking care of my elderly Nanaji (Moms father) who has passed away in approximately 2013. We found out about this Will when he passed away, but we did not take any action at that time. Basically, my Mother has been stripped away by her Father of all the property she would have inherited. We are not 100% sure that the Will is registered or if my cousins made a fake Will because my Nanaji was blind so he would not be able to tell what he signed, also he had a drinking habit so the Will could have been forged when he was under the influence. My mother was the heir to estate of all the property because she is the only daughter, what action can we take to get the property back or our rightful share.