Update: Her vet wants to wait a month to see whether the dog will "grow out of it." The articles I read said that surgery should be done ASAP so that the muscles, which will hold the leg in place after the ball of the hip is removed, do not atrophy. You can try treating without surgery, but it almost never works, and requires the dog to be crated for SIX MONTHS, not ONE MONTH, for the dog to "grow out of it." And that approach is not recommended. I suggested she read the articles I sent her. Nope.
Now her vet says the puppy has the defect in BOTH rear hips, but that he can do the surgery himself. He's not an orthopedic vet, so that's a really dumb idea. He's also the vet who did the health check on the puppy before she bought him. I guess he intends to make sure he gets his cut of the profits. I would never have a general vet do that kind of surgery on my dog. But I know better than to try to tell my sister differently - she still thinks he walks on water. So I will say nothing.
If she couldn't afford a specialist, it would be a different story. But she can, easily.