Transfer fee applies only when a society member sells his flat
In your case your seller was not a society member when he sold the flat to you
So where is the question of paying transfer fee?
Society has to issue you share certificate in which your name will be stated on its face
Your name has to be stated as primary or original member and not in the transferee column
Obviously the seller cannot be a primary or original member as when he sold, society was not even in existence
If what the society is demanding is to be accepted then for all sale transactions done prior to society formation, transfer fee would become payable, which obviously cannot be the intent of the law of charging transfer fee
So neither you nor seller are liable to pay any transfer fee
You have to take legal action against society for making such illegal demand
Write to registrar of societies and mark letter to society. Do follow up of letter through RTI
Please note your seller is not liable and no legal action can be taken against him as may be suggested by some panel member here (which i learn from your follow up queries, that such a suggestion has been made, which is erroneous)