The ABC TV reporter outside the police station said that HP's lawyer walked out the front and around the corner (obviously to distract reporters) while HP left by the back entrance in a white commodore and that police say she has not been formally charged with any offence.
I think HP is the person who originally tipped off Crimestoppers that she thought the remains at Wynarka might be Khandalyce.
I expect her partner left earlier with the child to go to a neutral point unknown to the media (friend or family home perhaps) and HP has now left to join them.
To me, she just doesn't look like she is guilty of anything.
I know we hear the euphemism "helping police with their enquiries" as "about to be arrested", but sometimes real people actually are helping the police with their enquiries.
She seemed to have that shopping bag full of documents with her and she seemed to be handing them over to the police, so I'm thinking she is a willing witness, not a suspect.
Possibly she has been living with a suspicion about what happened to K and K for years and yet, given that there was no evidence they were actually even missing until a couple of weeks ago, perhaps she thought she was being silly and said nothing until the names were released.