After father's death I want to sell the Flat owned by him to support my family. How?

Hi, Last year my father passed away suddenly and had made a registered Will in my name for the flat in question which I want to sell to support my left behind family- 1. Mother and 2. Younger Brother. The registered WILL was made in West Bengal when my father was alive [clearly mentioning me as the Executor of the WILL for this property after his death] and the property is in West Bengal itself. I live abroad status NRI and helping my family to sort this matter out. My younger brother lives in Mumbai and my Mother lives in her own house in Rajasthan but recently moved to Mumbai [She is not well and can not walk due to problems and currently getting medical treatment] to live with my brother. I have a buyer for the property in West Bengal and he wants an affidavit from my brother and mother saying No objection for me to execute the sale. Could you please guide me : 1. What wording or language [or if there is exact form available online for me to download] to be written exactly on the affidavit and on how much value in ₹ the stamp paper in Mumbai so that my lawyer in West Bengal can accept the affidavit as he has no knowledge about Maharashtra laws. 2. My brother has PAN and Aadhar as per mumbai address but my mother has no PAN but has Aadhar card having address of West Bengal. Kindly advise on the above matter at the earliest.