H1B Sponsor and GC Sponsor can be different..?

[RoyR]

Hi,

I wanted to initiate GC in EB2 and I'm on H1B status. I found a consultant (Company A) who will do the H1 transfer and start the GC in EB2, but the Company A is hiring me for a full time opportunity with another company (Company B) who process GC only in EB3. So after the I-140 approval I want to transfer the visa again to Company B. But the GC will remain with Company A, which they wont revoke and informed after 8-10 years at the final stage I need to be join them back again and get the GC. I wanted to know the answer for the  below 2 Questions

1: whether this is legal and any issues if one company holds the H1 after I-140 approval who will  be my employer and other company holds the GC.
2: While stamping in India after I140 approval, whether any rejection because I140 is approved for one company but I work for another company