Buy a stuffed animal Frenchie that looks like yours.
Lay it on the side of a road that you drive by frequently. Take your kids out for a drive while your wife gives the real dog to new owners.
Drive by the stuffed animal fast enough for them not to get a clear look, but slow enough for them to think it’s their dog.
Get all upset and talk to them about the importance of taking care of their animals and why you’ll never get one again.