Is it not likely that the insurance position is similar to that (for the UK at least) for motor vehicles.
UK law says that having issued a certificate of (motor) insurance, an insurer is always responsible for third party claims and cannot avoid them. This is regardless of what the insured may have done (i.e. drunk driving is in breach of insurance conditions but anyone you injure will be able to claim).
Not in aviation.
That's exactly what seems to happened in the Graham Hill case?
AFAIK the GH estate got simply stripped by the lawyers acting for the estates of his dead passengers. But details on this case, interesting though it is as a precedent, are very thin on the ground.