Property Transfer Procedure.

Hi, My Father passed away in 2004 and he had nominated me for the flat. The nomination form was already submitted to the society before he passwed away.Had a word with my society. They just asked me for a NOC from my brother and than they would add my name in the share certificate and add my name in the society registers. I do not want to sell the flat. 1) Do I need to register the flat in my name or its optional? 2) How important is mutation? I was just planning to get the share certificate on my name by submitting the NOC to the society. Will it create any problems if i dont register the property at this. Regards, Khimji Patel