Are these councillors raising the issues during council meetings? If so, there needs to be an agenda item to discuss it and if there isn't the Chair and or Clerk could stop the discussion on those grounds. If the dispute is between the councillors and the neighbour then really, it is not the council's business to discuss or to get involved with. If it is directly connected to the council, then the Clerk should take charge and deal with it from that point onwards.
Another thing to consider - if it is a legal issue against the council, it needs to be discussed in closed session and the neighbour could have grounds for litigation if their dispute with individual councillors is being discussed in a public meeting.
More information is needed as to the nature of the dispute before any concrete advice could be given.