You know that father sans a leg that was the reason that the little girl jumped Ed and took his auto-mail leg? Ever wonder how his likeness to the Hohenheim revealed in episode 43 is striking? As if the other father was Hohenheim, but aged?
Maybe the father that showed up at Rizenbul wasn't the father, but something else. Obviously not a homunculus, because they cannot use alchemy. Yet, Hohenheim claps his hands and uses it without a problem. But the other homunculi knew him, as well as Lyra/Dante. How? Is he really human? Or is the other father sans leg Eds real father (and I guess it pretty much goes together, since the Hohenheim at Rizenbul has an obvious lack of sense of time, and he looks as if he never aged), and he lost his memory, which is why he clings to his grandchildren, which means after the war, something happened and he lost his memories as well as his leg, so he builds a new family. Odd, because there is no evidence that he was ever married. Then how is this other father created? He isn't human, that's for sure.
Just that last look in the episode gave me vibes. Is this bizarre, or what?