I, Epiren of the K, shall lay claim to the final member of the Tohno household:
Tohno SHIKI!! of the Tsukihime (+ others) franchise
Unlike the faker Nanaya, he is the real and only family in blood to Akiha Tohno - most of the time crazy and thirsting for blood, he acts like a bro to Nanaya in one of the routes, even as going as far as having a round of coffee.
However, in the 'canon' ending (or so it would seem, though Melty Blood and the Manga [and that atrocious anime] both support this claim) he is replaced with Michael Roa Valdamjong - the vampire who had taken residence and finally dominance over SHIKI.
Still unclear whether they are two separate entities, but I like SHIKI over Roa.