Not sure I like the 4th member becoming a succubus as well, sort of ruins the lovey dovey feeling the first part had. Especially as they went as far as to hypnotize him in the first one because they didn't want to fuck a stranger, but now that he is a succubus they should need a new source since presumably they can't truly supply each other, just share what they have. Eventually diminishing returns would force them to find a new source of vitality in order to survive.
Base +6, SomeUne -6, kamisking +6, nanaya666 +6, Kraftz +6