So if I have to use AC21, how do I show proof that my I-140 has been approved?
--- After I-140 approval the USCIS will sent I-140 approval to the lawyer and may also send curtsey copy to employer
If its the employers document, my lawyer will most likely refuse to even give me a copy.
---- If your employer requests then lawyer will give you the copy of I-140 approval.
** Try to get copy of I-140 filing receipt from lawyer or from employer HR that I-140 filing receipt has your case# and later you can take a printout from BCIS Online status punching the receipt # and that will be the proof that I-140 has been approved, the case # will match with the receipt #. Better also to get LC approved copy that is with lawyer because Form ETA750A is with LC approved package. If you want to use AC21 in future then new lawyer can look at ETA750A and will write the same skill or job title