I am sorry for your daughters lamb and your daughters feelings, why were the puppies not being watched and were able to get to the lamb?
Why would they be harassing the neighbors stock? Are they not contained? Do they run loose? I am surprised the neighbors have not shot them for chasing livestock.
Quit blaming the puppies, try building a fence or kennel and do some training.
Wait, on second thought, maybe sending the puppies back to the BREEDERS will at least keep them alive.