A person cannot enter the US as a visitor with the intent to adjust status...... "special case" or not. That is fraud. It is a violation of the VJ terms of service to suggest fraud. Attorneys don't always give accurate information.
She cannot solely sponsor her parents without sufficient current income or assets. She will have to find a willing, qualified joint sponsor. She has the right, as an American citizen, to petition her parents.
Chances are very low.....There are people who have entered with no problems after far more than 3 years. Otherwise, you are looking at 2 years for an IR-1.
Good Luck. I'm out..
@Mike E might have something to add.
You have a valid Green Card. You are a legal resident. CBP cannot not deny entry. Worst case scenario is they ask you to sign an I-407. If they do, just refuse.
The withdrawal letter for the I-129f is irrelevant. The two I-130s are different visa categories and probably different USCIS service centers. Sometimes, it takes a month to get initial receipts.