I had absolutely no illusions about our chances of getting Toadface Umbridge's permission to operate legally. Unexpectedly, Harry solved the problem, thanks to his friend Dobby the freed house-elf. He found us a wonderful room that none of us had ever heard of, that only appeared when needed, and appeared with whatever the person who had "summoned" it needed within it! It was called the Room of Requirement. Had I only known of such a thing before...but no point in vain regrets. And, yet again, my view that house-elves would make wonderful allies was vindicated. Even if they can't or won't act directly against their masters, they often have access to many secrets.