The above posts suggest a roundabout - 回复：请教关于485 relink

The above posts suggest a roundabout for those applicants whose I-140's priority date not being current to file I-485 earlier, by filing another EB-1 I-140 together with I-485 in hoping to transfer EB-1 I-140 based I-485 to existing PD not being current I-140 and then drop EB-1 I-140. 

It is impractical for above scenario, unless the EB-1 I-140 is approvable otherwise the I-485 is not approvable, as it does not comply with INA 245(a)(3) - "an immigrant visa is immediately available to him at the time his application is filed".

An example is given in I-485 被拒若干例