I have a pending AOS (I-485) application filed by my previous employer (company A). The I-140 is approved and is well past 180 days. I moved from company A to company B in late April 2008. They did an H1 transfer and filed for AOS portability under AC21. I did not like the role there, so had planned a move to Company C, my current employer - again H1 transfer and AC21 (yet to be filed). Just before I moved, I got another offer from company D (which I believe best fits my long term career interests). I would've avoided the hop to company C had I not given the notice to leave at Company B. Now, I am looking to move to company D at the earliest (perhaps in a month). I have been at company C for 4 weeks now. Question: Should company C file an AC21? Since there is already an AC21 on file (by company B) and if I will move to company D, can I reduce one additional AC21 filing? This is just so that there aren't 3 Ac21s filed and to avoid making me look frivolous. Please advice. If its safer to file it, I can request an AC21 filing soon from company C.