Again where is the proof of lineage and registration papers that show these were in fact APBTs? Without them they are just mutts who have a very poor temperament.
If it walks like a pit bull, barks like a pit bull, attacks like a pit bull, the inspector is going to cancel your home policy.
Proof of lineage not required.
You are clearly vested in trying to save the image of a dog that has a bit of a temperament issue to start out with. Yes, towards people, they tend to be very good (despite public impression) but they tend to have issues with other dogs, which can lead to problems.
Again though, for insurance reasons, if its partial, its good enough.
Dan
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Forgot to cite my source for the issues with other dogs comment.
American Pit Bull Terriers: What's Good and Bad About Pit Bulls