I am just wondering what decisions, or group decisions would make anyone else in a group liable in the event of an accident?
The list is endless, if, fortunately, the occurence rare.
The group member responsible for insurance "overlooked" to renew. Another group member is involved in an accident during this uninsured period. The group member "overlooked" to check the documents before accepting the aircraft, or was assured by email the documents were in hand. I am sure you can invent plenty of scenarios.
Most groups never have an issue and when they do the insurance takes care of it. I am not going to exagerate the risk, but if things go really wrong the additional protection of a limited liability may be worthwhile.