Letter of Administration

My client's mother�had a Locker in State Bank, there was no nominee registered to the Locker. She passed away in December 2010. A petition was filed in Barasat Court by my client's father, successively the contents of the Locker was valuated by a Jeweller, a print ad published as a formality, the LOA was issued in the name of father ( my client testified in court as they were joint claimants). The maximum stamp duty was paid in court The LOA was submitted to Bank and they had sent the document for searching. Father passed away during this process in March 2016. The attached LOA is in my client's father's name . My client is the sole claimant to the asset. The LOA has to be transferred to my client's name. The locker contains jewellery of my client's mother and wife. Now my question is is it possible to substitute the person in the same case where already LOA is granted in name of my client's father? OR I have to file a fresh case? Thanks in advance.