Oriental Bank Of Commerce — Locker issue

Hi,
My father had a bank locker in OBC bank India that had been open in 2014 along with saving account. Bank updated my self as nominee in saving account but not update nominee in locker.

My father passed away in 2019 . As of now as per bank there no nomine in locker

We are 4 legal hire of this locker including my mother . One of my sister is not willing to take any action on this matter neither favor nor against . Due to which a common agreement is not possible. We tried all way but she is not agreed.

Bank is also not willing take any action on this and we are struggling for last 3 year .

Two members are ok to allow mother to open but due one sister (Settled in abroad) we are help less.

Please suggest what could be way to resolve this .

With Regards
Deepak