You know, this theory is actually plausible. It is true that Chie is excellent at collecting information from photos, hacking computers and such. And she might stick with :re for a little while (probably for Shuu's benefit), or at least be acquaintances with :re. But I don't think that anyone will be investigating Kaneki's past for awhile (or it won't be revealed for awhile), because :re and other characters seem very preoccupied with the new developments in the series (it doesn't seem like things are settling down like typically after an arc). But perhaps Kaneki's action of throwing Shuu off the roof or his new behavior will lead an :re member or someone else involved with Kaneki to search for more information regarding him (such as Eto, though she might already know everything and it is waiting to be revealed). I think you should post this theory in a blog, it actually seems like a legitimate possibility.