I have posted my opinion and unfortunately, it disappeared from the post.
A banker is not concerned with legal heir matters.
The relationship between Depositor and bank states that the money has to be paid either to any of them or survivor and his job is not of trustee to find legal heirs and adjudicate on the issue.
A banker is supposed to implement the mandate given to him and the payment is treated in due course if he follows the mandate unless he is restricted by any legally valid orders against such payment to the survivor.
Members cannot advise or judge on your claim is in order or not in claiming the entire money was yours and on that you need not legally bound to share it amongst legal heirs.
If the Banker pays you are legally entitled to receive that money as trustee and can keep it till there is a claim from legal heirs. Legal heirs can also challenge your entitlement. and proceed against you depending on merits of their case.