Property transfer for registered will

My grandfather owned a house and he passed away. There was no nomination in the society records. Grandfather did make a Will which was registered. In the will, he has mentioned that the property should be given to his son and he has also mentioned in the will that his son should be made a society member. Now the society is asking for probate of the will. However there is no way to get the Will probated as Pune is not a metro city and as far as what I have found out, probate happens only in metro cities. Succession certificate won't help as it will have names of all my grandfather's son and daughters. Whereas grandfather has mentioned in the will that he wants to give his property to only one son.