Registration of flat jointly owned

Hi, My husband passed away a year ago leaving an unregistered will in my name with witness signatures where he specifically mentioned all the immovable properties. I want to mention we stay in bangalore and we have a registered flat in bangalore and another yet to be registered flat in Bhubaneswar, Odisha. Both the flats we both are joint owners in documents and also in loans. The bangalore flat got transfered in my name without any hassle based on the WILL , surviving family member certificate issued in bangalore. I have furnished all the docs to the builder of my Bhubaneswar flat including an NOC from HDFC for the registration of the unit. Now the builder of bhubaneswar flat is asking more supporting documents like succession certificate to make the property transfer documents in my name for the purpose of registration. The surviving family member certificate includes a sentence that "it should not be treated as a legal heir certificate" for which the builder has apprehensions. Please guide what actually should be done and where it should be done(where the deceased was staying during death or the location of property)