These are what are known as "Interested Parties" meaning the Claim would directly effect them. As far as I know they would have to join the claim at an early stage. One thing that needs to be remembered in all this is that if this case goes to Court the Judge is not going to award damages to anyone or put the medical profession on trial.
In my view that sounds like a strawman argument. Yes, legally they may not be able to bind medical staff, but medical staff are bound to guidelines. A doctor would have to have good arguments for deviating from them before a court. It would always be a decision from case to case, and I doubt a deviation would be accepted on a broader scale.