Here are my thoughts:
Karli was not receiving a single parent pension as she was in a relationship with someone who had money by other means.
This person killed Karli and Khandalyce (Not sure on who first; Karli if planned, Khandalyce if child abuse and the baby died). He had to kill the other one to cover his tracks.
As other people knew they were in a relationship he could not risk the bodies being found together as it would link him to them almost immediately. So when friends/associates asked where they were he would have said they have left, gone home to Alice, run-off with some else etc, etc. No-one would question it further. If Karli died first people would question why he was left with a toddler….
Karli’s car was then signed over and sold to the man ruled out as a suspect by the partner/murderer/friend.
This is why multiple raids, because them being a relationship would be common knowledge and they may have lived with others as they were travelling.
I think the investigation will move incredibly quickly now they have been identified but if the suspect is already in jail they will take their time to get a watertight case, there is no rush. There probably won’t be any physical evidence linking this man to Karli or Khandalyce (maybe Khandles through DNA or fingerprints inside the suitcase) and so it will come down to witnesses being willing to say they were together, he explained the ‘separation’ this was, he was the one that sold the car, etc, etc.
I do believe Karli or the partner were involved in criminality which is why a second missing person report wasn’t made… the family, cousin etc may have not wanted to get her in trouble. Hindsight says what a shame the report wasn’t made earlier. Yes they would still be dead but greater chance of a successful prosecution.
I may be completely wrong perhaps she was a single mum (no relationship) the whole time but I don’t think so. The way she dressed, the slight frame, I cant see her not have a boyfriend/relationship.
The money a person would earn from fruit picking would be much less than what a single parent pension would be paid and how would you pick fruit for 10 hours with a child in a stroller nearby, just not realistic.
Also about the last photo of Karli. It is quite possible she was simply feeling down, tired, whatever and didn't want her photo taken that day, that's why she is not smiling.