Could Megumi Be Jirou and... uhh.. Whatshername's(YURI!) Daughter?

[Black Fang]

Besides maybe Jiro and Otoya's are the parents. Remember Jiro only takes the form of a human male. *wink wink*

Not necessarily. It could easily be the other way around. Remember that werewolves in myth are simply humans or human-like with a monstrous wolf form during a full moon. Some classic vampires can turn into bats. The same principle probably applies here.