Sister claim on dead bachelor brother's assets and money

1) Dead Bachelor Elder Brother 2) Married Sister 3) Younger Brother -- 

Fact: Few days ago Bachelor  Brother was Dead and He did not made any Will 

        Younger Brother already hide Land Documents / Bank Pass Book and Post Office Certificate

Married Sister Wants : -- YOUNGER BROTHER CAN NOT DO IN ITS OWN NAME

Need Advice :-- Without Court Case , How to stop Younger Brother's Activity in this matter ????

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