sorry to hear you are having problems with your dogs, i would suggest that you try walking them seperately. this way you give each dog some individual attention and also can do some training as you are going along, make it fun and keep it short. even though borders are usually good natured little dogs i'm concerned about the face nipping. If it happens again, try saying No in a sharp voice, or Oh it usually works they wonder what's going on, borders are sensitive little dogs and aim to please, hope this gets resloved soon for you