I mean, sure, but why not just use multiple keys? You don't need anything more complicated.
Discussion
That defeats the purpose of interconnectivity which is one of Nostr's big selling points. Until then I use Amber for everything I can, but their security hasn't been 3rd party audited, and that's understandable since an audit is ~$15-20k, but it's still important to note as Nostr grows.
I guess I'm not understanding how it's difficult to manage a few sets of keys. If you have the keys, how is it different than a more complicated set of child/parent keys.