Is An Affidavit Made Before 1 Cls Judicial Magistrate Enough For Succession

My bachelor paternal uncle made a hand-written will favoring me as his successor. When he died, he had only his brother i.e. my father and three sisters. He had his own house in Howrah district and paternal at Purba Bardhaman District. He had some mutual fund yet to recover. And nothing except these is in any other district/state. Next year one sister died. Due to monetary problem this will is yet to get probated. Certainly 2 days back my father got a copy of an affidavit made before a first class judicial magistrate of Alipore (24 parganas) court by the dead aunt's son & daughter claiming his property. My question is -- 1. If such an affidavit is enough to claim his property. 2. If Alipore court judicial magistrate can give them any such affidavit on Rs. 10/- non-judicial stamp paper. 3. Shall I have to do anything now or may wait. 4. If the validity of Will has any expiry date. 5. If I do nothing now, can I fight in future.