You need to understand a couple of things: A Swiss Shepherd, IS a German Shepherd, bred for the white color which is a fault in the SV and the AKC.
As with any breed being bred for a specific color, the gene pool is being limited, and making this a separate breed will mean that out crossing will end, and the dogs will be even more in-bred and that in itself will not hurt individual dogs, but recessive genes will be on both sides of the equation and so, whatever is there, will come out in puppies with a greater frequency, in health, conformation, and temperament.
I've seen white dogs. None that I want to own. Back in the 80s, 90s, there were some that temperamentally were unstable, fear biting dogs. Has it gotten better? I really don't know. Those that bred the white dogs, were those that were ok breeding outside of the standard to meet customer wants, in color alone, which means, not necessarily breeding for structure or health.
More recently, since they can be shown in UKC here in the states, there are some breeders of the white dogs that are, in ways other than color, following the standard, and testing their dogs. Also I've seen a few in obedience classes that were nice dogs. So maybe things are getting a little better.
Evenso, if your mom is afraid that the dog will be dangerous because of the breed, in this instance, she has made it more likely to get a less than stellar dog, by going Swiss instead of German. You are more likely to find a good GSD breeder and a GSD of excellent character than a Swiss Shepherd.
Now for this pup. For the dam to bite the pup so hard as to cause puncture wounds and dislocate the jaw, I think that is all you need to know. The pup gets 50% of its genes (including temperament) from this bitch, but it has also been imprinted (temperament) by this bitch. Double whammy. It has also had a serious injury/incident at a time when learning is concrete. The dog is likely to have lasting issues with dogs, or at least require seriously careful socialization.
I think you should return the puppy as hard as that sounds to the breeder. They are responsible to deal with problems in their breeding stock. And for you to take on that, it just makes it that much easier for them to ignore that they have something seriously wrong with their breeding bitch to do such a thing.
If the bitch that did the biting was not the dam, than they have something seriously wrong with the management of their dogs/kennel. It is there problem, and I am concerned with your mother's overall experience with this dog, if you are to keep it. It will make her impression of the breed that much worse.
And, I agree, bringing the puppy and asking you to try it for a week that was foul. She should have called you on the phone and explained the entire situation and offered to hang onto the puppy until it was healed, and to work with the puppy around other dogs, to ensure he "forget" the negative experience.
I have had 19 litters in 12 years, and I have never had a bitch make a mark on her 8 week old (or younger) puppy. There is something wrong with a bitch that does this, and the puppy, most likely, has that in its genes.
Jenna, RN CGC & Babs, CD RA CGC HIC
Heidi, RA CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC & Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly CGC & Bear CGC