H1 transfer during I-140

[gavishnu]

I had my I-140 approved 2 years ago and currently looking to transfer my H1B to another company.
Now I got some questions but going through various posts online, I am left with more confusions than answers.
Here is what I need to know -

1) It seems that the current employer A cannot revoke my I140 in case of my relieving as I have been with the company for 2 years after my I140 approval. Is that correct?
2) Once I switch to the new employer B, is it mandatory that B should restart my GC process from the beginning? Or can I keep the I140 from A?
3) If the employer B does not restart my GC process,
a) Can they keep extending my H1B based on the I140 approval from A in the future?
b) If needed, can I move to company C in the future with the I140 approval from employer A? Or will this create any problems in the future?
4) Any other comments?

Greatly appreciate any response, it would be really helpful for me.

Thank you!

[francesjacobgreene]

I had my I-140 approved 2 years ago and currently looking to transfer my H1B to another company.
Now I got some questions but going through various posts online, I am left with more confusions than answers.
Here is what I need to know -

1) It seems that the current employer A cannot revoke my I140 in case of my relieving as I have been with the company for 2 years after my I140 approval. Is that correct?
2) Once I switch to the new employer B, is it mandatory that B should restart my GC process from the beginning? Or can I keep the I140 from A?
3) If the employer B does not restart my GC process,
a) Can they keep extending my H1B based on the I140 approval from A in the future?
b) If needed, can I move to company C in the future with the I140 approval from employer A? Or will this create any problems in the future?
4) Any other comments?

Greatly appreciate any response, it would be really helpful for me.

Thank you!

Answering this question with the appropriate level of completeness would take many pages, but I should mention that I wrote about this topic extensively in my book with lots of common examples. Check out the link in my bio. It covers all your questions.