No, I actually think Corporate AU is less funny if Fritz/Heinrich is a thing, since it's not canon -- unless the whole story were focused on Fritz/Heinrich crack instead of primarily on corporate AU crack, which would be a very different thing. I think a lot of the humor comes from juxtaposing canon relationships or at least canon emotions with the crack AU. Well, within reason -- I see your point about it being hard to retain all the relationships, and e.g. if you retained Fritz and Heinrich's siblingship I could see Wilhelmine being a close friend or coworker. Or vice versa, but I think it's easier to see how to crackify the Fritz and Heinrich brother relationship than the Fritz and Wilhelmine brother-sister relationship in this context.
Re: Alert
No, I actually think Corporate AU is less funny if Fritz/Heinrich is a thing, since it's not canon -- unless the whole story were focused on Fritz/Heinrich crack instead of primarily on corporate AU crack, which would be a very different thing. I think a lot of the humor comes from juxtaposing canon relationships or at least canon emotions with the crack AU. Well, within reason -- I see your point about it being hard to retain all the relationships, and e.g. if you retained Fritz and Heinrich's siblingship I could see Wilhelmine being a close friend or coworker. Or vice versa, but I think it's easier to see how to crackify the Fritz and Heinrich brother relationship than the Fritz and Wilhelmine brother-sister relationship in this context.