A few ideas. 1.Potential for mass hallucination as the whole family has had experiences, though each one was separate and distinct. Any known gas leaks or nearby production facilities? 2. Transdimentional being? Too big to exist within that confined space, too fantastic and improbable a creature to exist at all within our reality. Makes a kind of twisted sense. Also, all the more likely to occurr when no one is around to see it. 3. It was a figment of your very powerful sleep addled imagination. 4. It was forgetful and missed it's summoning ritual.