Sale deed in co-operative society pune

Hi,

This is regarding the Flat that I bought in Pune. I did the Agreement to Sale with builder for my flat back in 2005 and after that I got the possession in 2008. But, I never did any Sale Deed with builder. Now my question is that do we need to have personal sale deed with builder OR the Conveyance Deed Deed, that society has, would work for all flat owners without needing individual sale deeds for each flat? 

Thanks

Sachin