The past is the past. You can't control what happened in the past, but you can fix the results of it. Blaming and bring up the past for any little issues you have with your horses now is not productive. You have had your horses for long enough now that it is no longer the fault of what has happened in the past. It is now your (and your family's) fault for allowing your horses to get away with this dangerous behavior with the farrier (and elsewhere per your other posts). You need to step up and take responsibility and either work with the horses/train them to get through this or find someone who will. If you are not willing to do either of those two things you need to look into re-homing them with someone who will.