The Melinda Doll?

Interesting crossover of theories. Perhaps the Melanie/Melissa doll are both slight typos for what could be the Melinda doll - something which maybe acted as a benchmark for identity reversal, which was named after the technique developed by Melissa/Belinda, or perhaps it already existed, and they used the underlying principles of it to fake their own disappearances.

Yes, it would seem that stay-in-your-home-with-multi-tv-channels-and-directly-distributed-media-and-sustenance lifestyle is causing individuals to become more isolated from one another on a real-world level, but more connected in the digital-realm. This closely mirrors the idea of a replica world overtaking the 'real' physical world and becoming the place where people primarily exist. Myspace, Facebook, Twitter, Second Life, online PRGs etc. - all contribute to this, creating a collective mind in cyberspace and leaving the physical realm as some sort of ghost world; an abandoned, largely uninhabited industrial space on the edge of a retail town. Also ties in with the op-art-town-planning-herding/controlling of human movement manifesto.

I think Happy believed Cate n Grant to be a couple (assuming this girl was Cate), but possibly only because he was infatuated with her, so imagined her and her male companion to have romantic links. It is entirely possible that he was erroneous about this and that their connection comes down to being memers of a common group.