Help... Vin #'s dont match

Whole fronts rears even frames of trucks get replaced every day on wrecked cars with new and used parts no law is required to be involved as no laws are being broken just because some heavy. Collision repairs were done in the past does not make anything illegal. Again there are a lot of keyboard commandos who all "know" in depth history of a car from a couple paragraphs from a auto owner who is learning....