I'm not sure what you mean by "every character stacked".

So far as I'm aware, most multiboxers simply have the other characters on follow. That's certainly how I do it. Trying to move all 5 characters at once would be a nightmare, as each character would have - even with some effort put into it - a slightly different point-of-view, so for example, if you passed the movement keys through to each character, they'd all head off in a slightly different direction.

For me, they're always on follow except for when I use positioning macros to spread them out for big fights.