I remember watching this movie on TV a few years back, though I can't seem to find the name of it. It's about this group of half-vampires that were humans before but were tricked by this man who was a full vampire. They escaped from this white room he trapped them in and they got blood by having sex with their victims and taking it when they were unsuspecting. One of them had a sister, who got caught up in the whole thing and she later turned into a full vampire because two of them combined their blood as "two halves make a whole". They fight the guy, who tried to summon this monster or something... Anyway, that's all I have, and I would really like to know the name of it... Thanks!

I read a book that sounds similar, maybe it was made into a movie. The series of books were The Vampire Legacy, the first one is called Blood Secrets the second is Bitter Blood and the third is Blood Ties. The books are by Karen E. Taylor. Maybe you could search movies with screenplays adapted by her. Good Luck.