I-140 Approved, Joining new employer. Can I retain priority date?

[indgctrack]

Currently I am working for Company A.

My Labor was filed on Jan, 2010.

My I-140 (Under EB2) is approved last month. Now I am planning to join another employer (Company B, End client).

My questions are :

- If I join new employer, can I retain my priority date (PD for Labor filed through company A)?

- For the continuation of my GC, my new employer is required to file only I140 again OR Labor+I140 OR nothing?

Thanks