Treasury is the de facto owner of the companies, having rights to (more than) all of FnF's net worth and income due to the liquidation and dividend preference of the senior preferred shares.
FHFA has total control over the companies as conservator.
Existing common shareholders do not own the companies at all. They have no economic rights and no voting rights. Nothing.
What they do own is the very bottom of the capital stack of companies that are in conservatorship and are hundreds of billions of dollars below their regulatory capital requirements. That does not at all entitle them to any specific percentage (let alone 100%) of the companies once they reach their capital requirements and exit conservatorship.