MUTATION OF FLAT PURCHASED IN KOLKATA WB

I had purchased a flat in Kolkata in 2016 through tripartite agreement between seller, developer and myself, but I didn't complete the mutation of purchased flat at that time. Now, I need to complete the mutation of my flat in my name. When, I checked the mutation status of the apartment through assessee number of the seller, it shows names of 7 other persons who owns the flat in the same apartment. Moreover, there are pending property tax dues against the seller's assessee number and NOC could not be generated online. I also have no idea how to get my assessee number. So, I cannot proceed with online mutation process. So, now I need to know whether I will need NOC for mutation of my flat purchased in 2016 and what exact documents are required to be submitted for mutation of my flat? I can only provide copy of sale deed, mutation certificate of the seller and copy of identity proof of the seller and developer.