JoeF, please help me understand your point.
Case 1)
Parents have valid B-2 visas, during B-2 valid period, I-130/I-485 are filed (I assume I-130 AND I-485 can file together, correct me if I am wrong), in this case, it does not matter if B-2 expires or not, parents are in legal status, “pending AOS”.
Case 2)
Parents’s B-2 visas expire, within overstay 180 days, I-130/I-485 are filed, parents are still in legal status since they overstay less than 180 days.
Case 3)
Parents’s B-2 visas expire, AFTER overstay 180 days, I-130/I-485 are filed, parents are subjected to 3 years ban. If they don’t leave US, they will be fine. I-485 is most likely approved.
In sum, as long as parents stay in US, no matter non-immigration visas valid or invalid, they are going to be OK as long as I-485 is approved, which is very likely.
Thank you