Moby
Dick
Todd might be a sociopath but I don't think he or his uncle's kill for the pleasure of it, it's all very matter of fact, doing what is necessary however bad that is without empathy. So they'd maybe kill someone who's done nothing wrong to get what they want, but with Holly there'd be really no need for them to kill her and nothing to gain by doing so, its not like she could ever pin them to anything so they'd really be doing it for the sake of it. Even for Breaking Bad, killing a baby just for the heck of it would be a new descent into darkness. Although I do envisage a opening of the final episode where a crying baby Holly is the only one of her family left.
It would leave the door open for a sequel where Holly grows up, finds a tape with all the history and goes on a mission to destroy the Nazis. Sorry, but leaving the youngest one alive in a family has many a time led to a revenge plot.