Talk to an aviation lawyer.
But I think you will find that as long as all companies are under one umbrella holding company there are ways to transfer expenses...ie holding company reimburses airplane company, and then holding company charges sister company. I'm not certain about sister company billing airplane company directly.
This all assumes that all travel is incidental to holding company's business, and that the travel itself is not THE business. Standard common carriage vs. private carriage rules apply.