Sorry to disapoint you maurya but once a file is an unparametised imported feature the damage has been done.
The best you can hope to do is to redefine the imported feature and mess around with the suface boudaries and vertexes. Generally this is nothing more than an exercise in frustration.
We use alot of imprted data at work - Unigraphics, Catia and Ideas, at best we can only add featues to the imported data.
If you are doing this professionaly you have to make a decision early on in the project whether to accept translated data or jump in and re-model from scratch.
Lots of Luck
Skuld ^_^
