Can I transfer I-485 basis?

My I-485 was filed on December 15 2002 based on my pending I-140 under category of EB2-NIW. However, another I-140 case of mine under category of EB1-Extraordinary Ability in the Science was approved couple of days ago while EB2-NIW is still pending since June 2002. So I am wondering if it is OK to transfer basis of my I-485 case from EB2-NIW to EB1-Extraordinary Ability by sending vermont center a mail. Thanks.