FIL offered my wife $8k to baptize our kids Catholic

My father in law is in his late 70s and is nearing the twilight of his years. He’s a devout Catholic and doesn’t want my unbaptized kids (2 year old, 2 week old daughters) to be stuck in purgatory for all eternity.

He has been pressuring my wife to baptize our kids in a Catholic Church. Gone so far as to offer my wife $8k to baptize our kids. We would not accept his money whatever we decide.

My wife and I are comfortably 100% non-religious. I’ve said I don’t really care about them going through with some type of ceremony if it him some peace. But nor I or my wife are willing to take any of the prerequisite steps involved in getting my kids baptized:

Taking classes, meeting with clergy, lying to a church and telling them we are going to be Catholic and raise our kids Catholic, arranging a ceremony, buying creepy white Leftovers-style onesies or whatever, etc.

We’ve talked about looking into a secular humanist church or something like that but I’m pretty sure it being a Catholic ceremony or at least Christian and my FIL being involved in the ceremony is part of the deal.

What do I do? My wife and I are not joining any church but I don’t want this man going to his grave thinking two of his grandkids are going to be floating in eternal limbo.