Scripting (Who gets what line in a Mix)

I'm mixing a chorus, but I started without a script in mind.
Right now, I'm working from the NicoNico chorus edition, but I'm having trouble figuring out where to put people. A lot of them don't blend super well together (that'll take editing.... 'kay.), and there are some parts of some of the tracks that just aren't usable.

Is there any good rule of thumb for scripting your chorus After you have all the submissions in?

well what you can do is group the vocals depending on the type(sweaky, average and so on) and set the lines like that.

(What is Swea--
Oh, Squeaky?
I might do that.
There's seven girls and one boy, (plus one girl who I can't get her track).
Should I pair like with like (squeaky with squeaky and average with average)?

(Thank you!)