Good Samaritan laws cover volunteers....I think.
On a ride a number of years ago a rider fumbled at a stop and went down sustaining a minor concussion. An nearby off duty paramedic medic gave some assistance. My daughter, an ambulance dispatcher was surprised they did in that the medic would beheld to a higher standard because of their training and risked repercussions. All well in the end but yeah legalities.Still wouldn't prevent, if a family member is deemed to have their injuries "made worse" by the actions of a volunteer, from some ambulance chaser from filing a lawsuit, and the volunteer needing to spend their money to defend themselves. In Ontario anyone can sue, you have to defend yourself until the court rules. In the case of a volunteer FF, they are employees of the local government and as such, get defended by the local government lawyers.