Nazifag is, by far, the most vulnerable foid. It would be not just easy, but absolutely trivial, to take advantage of her.
She's an idiot and she trusts you. Having Nazifag go along with what you say would not be hard. Some harsh words, a bit of manhandling and you could get her to do anything. She wouldn't resist much.
Now, there are a lot of foids that you could do this to. Fig, Enoe, Road...but all of those girls have friends that would catch on to what was happening, and you'd have a difficult time after.
But Nazifag has nobody. Her "friends" laugh at every word that comes out of her mouth. They purposely just keep her around for their own amusement. If she tried to tell them that someone is doing this and that to her, they'd tell Nazifag to shut up. They'd JOKE about what's happening to her and ignore her.

Moreover, the fact Nazifag gets to have any social interaction at all is because of you. If she didn't keep cooperating, you could withdraw your support for her anytime, which means going back to her "friends" for who knows how long. She would quickly figure out that just letting it happen is the only way for her to have a way out of starving alongside her family.