Mhm, but what would then happen if the Knights kill the Big Daddy? Poppy's mental conditioning doesn't go away after she's cured, and even then I'd think curing her would make her less useful than she is right now. But just as equally, whilst she's like this she'll still attract Big Daddies...personally, I think the easiest thing to do is have the Knights attacked by BD until Poppy steps in and gives the BD a stern telling-off. Perhaps even have it on their side, so to speak, because it's attached to Poppy and was practically made to escort her? Of course, to make it fair, I doubt it'll help in any other way than attacking anything that is attaching Poppy...

tl;dr - If we kill BD, Poppy will probably never help the Knights. If we don't kill the BD, then...i dunno, it might just be really wary of the knights and drag Poppy off every so often.

I'm swaying towards keeping BD alive, because it still follows orders from the higher-ups, and can be a brilliant, brilliant obstacle later on once whoever's in charge of the test subjects catches wind of the Knights and their snooping because Poppy won't allow anyone to kill her daddy. :<