Hi! I'm the CEO of Clerky — and you are exactly right to be careful, for the reason you mentioned.
If you have a non-US founder, the safest thing to do is to at least seek the counsel of a startup attorney. There are a lot of online services out there that purport to be designed for non-US founders, but they don't really do anything special other than make it easier to get EINs, bank accounts, etc. That stuff are annoyances, but not really what makes the non-US situation difficult.
And no online service, from what I've seen, can safely handle a subsidiary relationship like what you're describing. I would really advise against trying to do that on your own without an attorney.
It could very well be that you can still use an online service like Clerky for parts of your setup (especially since we have tools for working with attorneys), but someone good needs to do the legal analysis to see if that's the case, if anything else needs to be done, etc.
