Cidco Transfer

I had purchased flat in 2008 , now I want to sell it but it requires video transfer. The plot of the society is a tender plot, so Cidco Transfer at that time was not compulsory. Therefore l did not do the cidco Transfer at that time and the housing loan was also sanctioned irrespective of that. The bank did not ever demand it. Now I want to sell the same flat and Cisco Transfer has become compulsory.My problem is that , the seller who sold the flat to me has expired and his family is untraceable. I have the copy of registered sale deed with the saler made at the time of purchasing the flat in 2008 original of which is with the bank. I need to do Cidco transfer with the old seller as well as with the new purchaser. What is the legal remedy for this to do it in the absence of the old seller or his legal heirs? How can I do Cisco transfer to sell this flat and to finish off banks dues?