Bern, I agree with your theory. Misty was out for the night & came home to find Butterbean sleeping & Haleigh dead or barely alive. (The loud 1:30 an phone call, pacing & yelling?) Misty had CLAIMED that early in the evening she was watching a kids video in the livingroom with Butterbean & Haleigh was alone in the bedroom watching another video. (Some furniture could have fallen on Haleigh as she attempted to use the DVD player) But it does seem Haleigh had gotten ill on a blanket as an attempt to wash it was made.
All Misty wanted was Ron. She could not admit an responsibility in this.
She took care of Butterbean...He was easy.
She looked after Haleigh...Not so easy.
Misty wanted her own baby with Ron.
In an "altered state", she very well could have given Haleigh a "Valium" to calm down for the night.
IMO She called Timmy...Her favorite brother & where Joe was sleeping that night, where the van was taken from, & had these 2 dispose of Haleigh for her.....But WHERE?
...Past behavior predicts future behavior...