Have their parents ever visited the US (legally) in recent years, and left without overstaying?
If not, their visa probably won't be approved anyway with an LPR or USC daughter in the US (close relatives living in the US have to be listed on the visa application). So let them go ahead and apply for the visa ... after it's rejected the argument with your wife will be resolved, as they'll have no choice but to pursue CP.
And if she doesn't need your income or assets to meet the financial requirements of the Affidavit of Support, you won't need to be involved in their immigration process so you can stay out of it and let her and her parents do whatever they want.
PD: Jan 2003 (EB3 rest of world)
I-485 Approved: July 2007
I am a layman, not a lawyer. What I write here is not official or professional legal advice. In addition, my answers on this forum are specific to the scenarios discussed in each thread and should not be generalized to other situations.