My two cents worth. There are two ways the OC can move this forward both involve the OC making a claim.
1. Just make a claim and see what the insurance company does. The insurance company may ask for further information via a formal statement. This would need to be supplied by the relevant owner.
2. The OC can get a statement from the owner as to how the damage was caused. This can then be submitted with any claim.
If the insurance company decides to pay they can decide if they have grounds to pursue action to recover the amount from the relevant owner. In legal terms the insurance company “stands in the shoes” of the OC and are allowed to do this.