Nice plot, just one question
In the movie, Edward was cured because of sunlight -- like a phoenix, then he was bitten by Charles and cured him. But this is the only experiment he had. What happens if the cured vampire (2nd round human) is injected with 1st round vampire's blood again -- say, because of losing too much blood?
A 2nd round human is strongest, he can not be turned anymore
B He is turned again, because there's no clue of which species is better
Say, if it is B
1st round human (turned) --> 1st round vampire (cured) --> 2nd round human (turned) --> 2nd round vampire ...
It's far beyond over.