The only reason you have 20 companies that roll up to the same investors or parent company is because you're already trying to hustle tax law loopholes.
There is no circumstance ever where a company of 10,010 employees should ever get a "small business loan" because one spin-out of the 10,000 person company has 10 employees. That's absurd. Quite literally the only reason that 10 person company exists is to artificially reduce the headcount and liability burden.
Your example is a large company playing tax, accounting, and legal games. They should not be eligible for a PPP loan. Ever.
And I have no problem with using the law to minimize your tax burden. I have an S-Corp, so I'm doing that very thing. But I'm not crying over the fact that because of that, my PPP lender calculated my loan based only off of my salary, which is less than half of my total comp. It's the consequence of having a corporate structure the way I do. So it goes.