Wow. In my mind, the theories including premeditation sure bounce back to the forefront with this revelation. It also makes me think it's likelier that Terri passed Kyron off to someone else, because if she wanted him out of the picture one way or the other (to hurt Kaine or whatever), then why not profit from Kyron's disappearance as well? If she could not only hurt Kaine and remove the "burden" that Kyron placed upon her, but also come ahead somehow financially by doing so, then why not go for it all? Surely someone out there would be willing to pay for the privilege of Kyron becoming their own. (Shivers!) Simply "offing" him wouldn't offer the same advantage. Maybe to Terri, that type of scenario might be seen as a way to have her cake and eat it, too.
I now wonder if she had been planning this for months, and was just waiting for the perfect opportunity (Science Fair / talent show day). I wouldn't be surprised if, in her own mind, she was very careful to project a "perfect step-mom" image beginning around the time her son was removed from the house. That way, if/when she succeeded in making Kyron disappear, maybe she thought people would look back and think how helpful she'd been with his schoolwork, how much volunteering she'd done up at school, etc., and would think, "Poor Terri!" rather than suspect the truth. Actually, maybe everyone's (anticipated) sympathy was just another fringe benefit in her mind.
