She carried the girls to the neighbors. When the police arrived the vehicle doors were open.
So pretty sure they were left in the vehicle. She woke up from her drug,alcohol stupor, found them dead. Unbuckled them from their car seats, picked them up, then carried them to the neighbors, leaving the vehicle doors open.
If she's psycho enough to commit vehicular assault, she's psycho enough to leave her babies in a vehicle. In spite of all the warnings,and awareness.
It's the only logical conclusion imo.
That is the only scenario that fits, imo. What truly disgusts me is that I doubt this is the first time she's done this.