A friend of mine recently entered the US on immigrant visa and is still waiting to receive a green card in the mail. Her USCIS Online case status currently says "Immigrant Visa Fee Payment Received." Now she needs to leave the US for a few weeks due to family reasons. She has friends who can deliver her US green card (when it arrives to her US address) to her so that she has the card with her when she re-enters the US.
Can she re-enter the US with her green card if she left the US before being mailed? Will she be denied entry on the grounds that she had "abandoned" the green card application process? What documents (Advance Parole? I-551stamp? Change of Address??) does she need to prepare before she leaves so that she can re-enter the US?