wee girl

Hi. My father has 3 Border Terrier bitches he'd like to breed. (He's bred terriers for many years). Unfortunately, one of the bitches had Demodectic Mange as a young puppy so he's not sure if he should breed her or not. His vet says he thinks he can if it is localised as opposed to generalised but unfortunately, he doesn't know for sure which of the two she had (neither does his vet as it's very difficult to tell apparently). Has anyone had experience of this mite? Have you bred? What was the outcome? Will the pups be born with it? Has anyone actually bred a dog with demodectic mange? He has read a lot of articles on the subject but as yet has not had a definate answer or spoken to anyone who had actually bred. Appologies if I sound ignorant, I am not a breeder, just asking these questions for someone else. Thanks, any advice would be appreciated.