Withdrawal of money from joint account with either or survivor mandate

Hi, I am narrating a real life incident. A daughter has a joint bank account having either or survivor mandate with her father. Her father died roughly twelve months ago. Her mother died several years ago. She received a cheque of Rs6 lakhs in the name of her father after his death. She deposited the said cheque in the aforesaid joint account. Subsequently, she transferred the said money of Rs6 lakhs to her individual account in other bank. There are three other siblings apart from aforesaid daughter, meaning they are total four siblings. I am her relative and I know that aforesaid money of Rs6 lakhs belong to her, because she gave it to her father in cash and her father gave it to some other person through cheque. That person returned the money to her father through cheque. This is known to two other siblings as well and they will standby with her. However, one of the siblings may create problems for her owing to selfish reasons. - Is it mandatory for her to inform the bank about her father's death soon after her father died? - Can this withdrawal be rated as any fraud or is it illegal? - What actions can be taken against her and who can take those actions? - Can bank take any actions against her? - Can any one of the siblings claim his/her own right independently on the aforesaid amount? - Can all siblings claim their right unitedly on the aforesaid amount? - Any other implications or guidance. Would be great, if you can help in understanding the legal aspects of aforesaid matter, so that I can guide her. Thank you. C Patel