I'd like to know who REALLY took care of the baby when PF had her. I'm going to guess Not Him. I'm also going to speculate that he learned early and often to use the baby in whatever manner he deemed necessary, in particular to manipulate KB. We saw how he used the baby to manipulate KK. Try to confuse her sense of doing the right thing.
About that, what's the thought process to go from, "I'll drive for hours and hours to clean up a crime scene, I'll watch a tote melt in a fire, but no, nope, I draw the line, I won't take a body back with me". She didn't once think maybe her line not to cross might've come sooner than that???? Like a normal human being's.... like how about not participating in conversations, planning, and the carrying out of MURDER?
...
Nothing about PF tells me he's seriously interested in parenthood either. I don't think he has THE CAPACITY to consider or evaluate.... actually I can stop the sentence right there.
But I was going to finish: he doesn't have the capacity to consider or evaluate proper care of a child. IMO it wasn't HIM who had a concern about fit parenting but KB! And I bet, if she did question his parenting in any way, he decided he'd attack her parenting. That's how psychopaths work.
The only thing right about this whole case is that the little girl is in the care of the people who loved her mommy most.
My thoughts only