Bats can't transform into vampires outside of fiction; it's not a natural ability. I think it'd be too odd and doesn't offer enough unique abilities. For example, blood sucking could be achieved without transforming into a vampire -- some bats do drink blood in the real world.
Wtf do you mean by Transylvanian? You do realize Transylvania is a historical region in Romania? So by definition every person living in that region is a Transylvanian.. Why would you want to transform into a Romanian anyway?